On a Result of Hardy and Ramanujan

A Hardy-Ramanujan-Rademacher-type formula for $(r,s)$-regular partitions

Let $p_{r,s}(n)$ denote the number of partitions of a positive integer $n$ into parts containing no multiples of $r$ or $s$, where $r>1$ and $s>1$ are square-free, relatively prime integers. We use classical methods to derive a Hardy-Ramanujan-Rademacher-type infinite series for $p_{r,s}(n)$.

Ramanujan Cayley graphs of the generalized quaternion groups and the Hardy-Littlewood conjecture

In this article, we investigate the bound of the valency of the Cayley graphs of the generalized quaternion groups which guarantees to be Ramanujan. As is the cases of the cyclic and dihedral groups in our previous studies, we show that the determination of the bound in a special setting is related to the classical Hardy-Littlewood conjecture for primes represented by a quadratic polynomial.

Infinite sets of $b$-additive and $b$-multiplicative Ramanujan-Hardy numbers

Let $b$ be a numeration base. A $b$-additive Ramanujan-Hardy number $N$ is an integer for which there exists at least an integer $M$, called additive multiplier, such that the product of $M$ and the sum of base $b$ digits of $N$, added to the reversal of the product, gives $N$. We show that for any $b$ there exists an infinity of $b$-additive Ramanujan-Hardy numbers and an infinity of additive multipliers. A $b$-multiplicative Ramanujan-Hardy number $N$ is an integer for which there exists at least an integer $M$, called multiplicative multiplier, such that the product of $M$ and the sum of ba…

Ramanujan Summation and the Exponential Generating Function $ \sum_{k=0}^{\infty}\frac{z^{k}}{k!}ζ^{\prime}(-k)$

In the sixth chapter of his notebooks Ramanujan introduced a method of summing divergent series which assigns to the series the value of the associated Euler-MacLaurin constant that arises by applying the Euler-MacLaurin summation formula to the partial sums of the series. This method is now called the Ramanujan summation process. In this paper we calculate the Ramanujan sum of the exponential generating functions $\sum_{n\geq 1}\log n e^{nz}$ and $\sum_{n\geq 1}H_n^{(j)} e^{-nz}$ where $H_n^{(j)}=\sum_{m=1}^n \frac{1}{m^j}$. We find a surprising relation between the two sums when $j=1$ from w…

Ramanujan's {_1ψ_1} summation

This paper gives a short but reasonably comprehensive review of Ramanujan's {_1ψ_1} summation and its generalisations. It covers the history of Ramanujan's summation, simple applications to sums of squares and orthogonal polynomials, non-commutative generalisations, and generalisations to affine root systems.

关于与哈代-拉马努金问题相关的斐波那契和卢卡斯序列的丢番图方程

On Diophantine equations with Fibonacci and Lucas sequences associated to Hardy-Ramanujan problem

该研究围绕哈代-拉马努金问题，探究涉及斐波那契序列和卢卡斯序列的两类三次丢番图方程，找出了兼具哈代-拉马努金数属性的斐波那契数与卢卡斯数。

A generalized Hardy-Ramanujan formula for the number of restricted integer partitions

We derive the asymptotic formula for $p_n(N,M)$, the number of partitions of integer $n$ with part size at most $N$ and length at most $M$. We consider both $N$ and $M$ are comparable to $\sqrt{n}$. This is an extension of the classical Hardy-Ramanujan formula and Szekeres' formula. The proof relies on the saddle point method.

Efficient implementation of the Hardy-Ramanujan-Rademacher formula

We describe how the Hardy-Ramanujan-Rademacher formula can be implemented to allow the partition function $p(n)$ to be computed with softly optimal complexity $O(n^{1/2+o(1)})$ and very little overhead. A new implementation based on these techniques achieves speedups in excess of a factor 500 over previously published software and has been used by the author to calculate $p(10^{19})$, an exponent twice as large as in previously reported computations. We also investigate performance for multi-evaluation of $p(n)$, where our implementation of the Hardy-Ramanujan-Rademacher formula becomes superi…

A Hardy-Ramanujan type inequality for shifted primes and sifted sets

We establish an analog of the Hardy-Ramanujan inequality for counting members of sifted sets with a given number of distinct prime factors. In particular, we establish a bound for the number of shifted primes p+a below x with k distinct prime factors, uniformly for all positive integers k.

Explaining Ramanujan's "Unclosed" Comment in His Last Letter to Hardy

We study the $q$-series $F(q) = \sum q^{m(m+1)/2}/(q)_m^2$ and offer some commentary on why Ramanujan may have thought $F(q)$ does not "close."

Ramanujan and Koshliakov Meet Abel and Plana

The neglected Russian mathematician, N.~S.~Koshliakov, derived beautiful generalizations of the classical Abel--Plana summation formula through a setting arising from a boundary value problem in heat conduction. When we let the parameter $p$ in this setting tend to infinity, his formulas reduce to the classical Abel--Plana summation formula. Rigorous formulations and proofs of these summation formulas are given. In his notebooks, Ramanujan derived different analogues of the Abel--Plana summation formula. One particular example provides a vast new generalization of the classical transformation …

An Elementary Proof of a Theorem of Hardy and Ramanujan

Let $Q(n)$ denote the number of integers $1 \leq q \leq n$ whose prime factorization $q= \prod^{t}_{i=1}p^{a_i}_i$ satisfies $a_1\geq a_2\geq \ldots \geq a_t$. Hardy and Ramanujan proved that $$ \log Q(n) \sim \frac{2π}{\sqrt{3}} \sqrt{\frac{\log(n)}{\log\log(n)}}\;. $$ Before proving the above precise asymptotic formula, they studied in great detail what can be obtained concerning $Q(n)$ using purely elementary methods, and were only able to obtain much cruder lower and upper bounds using such methods. In this paper we show that it is in fact possible to obtain a purely elementary (and much s…

Ramanujan circulant graphs and the conjecture of Hardy-Littlewood and Bateman-Horn

In this paper, we determine the bound of the valency of the odd circulant graph which guarantees to be a Ramanujan graph for each fixed number of vertices. In almost of the cases, the bound coincides with the trivial bound, which comes from the trivial estimate of the largest non-trivial eigenvalue of the circulant graph. As exceptional cases, the bound in fact exceeds the trivial one by two. We then prove that such exceptionals occur only in the cases where the number of vertices has at most two prime factors and is represented by a quadratic polynomial in a finite family and, moreover, under…

Approximation of the Partition Number After Hardy and Ramanujan: An Application of Data Fitting Method in Combinatorics

Sometimes we need the approximate value of the partition number in a simple and efficient way. There are already several formulae to calculate the partition number p(n). But they are either inconvenient for most people (not majored in math) who do not want do write programs, or unsatisfying in accuracy. By bringing in two parameters in the Hardy-Ramanujan's Asymptotic formula and fitting the data of the two parameters by least square method, iteration method and some other special designed methods, several revised elementary estimation formulae with high accuracy for p(n) are obtained. With th…

关于Hardy-Ramanujan定理

On the Hardy-Ramanujan Theorem

本文证明了Hardy-Ramanujan定理的有效版本，通过Poisson分布点态控制ω(n)的移位经验分布，并推导了平方自由数类似结果、Chernoff估计、高斯窗口估计、中偏差上界和一致矩估计。

Linked partition ideals and a family of quadruple summations

Recently, $4$-regular partitions into distinct parts are connected with a family of overpartitions. In this paper, we provide a uniform extension of two relations due to Andrews for the two types of partitions. Such an extension is made possible with recourse to a new trivariate Rogers--Ramanujan type identity, which concerns a family of quadruple summations appearing as generating functions for the aforementioned overpartitions. More interestingly, the derivation of this Rogers--Ramanujan type identity is relevant to a certain well-poised basic hypergeometric series.

筛集上的Hardy-Ramanujan不等式及其应用

The Hardy--Ramanujan inequality for sifted sets and its applications

本文建立了适用于筛集的Hardy-Ramanujan不等式加权版本，并将其应用于多个数论问题，包括大偏差、乘法表问题和移位素数因数等。

An Elliptic $BC_n$ Bailey Lemma, Multiple Rogers--Ramanujan Identities and Euler's Pentagonal Number Theorems

An elliptic $BC_n$ generalization of the classical two parameter Bailey Lemma is proved, and a basic one parameter $BC_n$ Bailey Lemma is obtained as a limiting case. Several summation and transformation formulas associated with the root system $BC_n$ are proved as applications, including a $_6ϕ_5$ summation formula, a generalized Watson transformation and an unspecialized Rogers--Selberg identity. The last identity is specialized to give an infinite family of multilateral Rogers--Selberg identities. Standard determinant evaluations are then used to compute $B_n$ and $D_n$ generalizations of t…

Some implications of Chu's $_{10}ψ_{10}$ extension of Bailey's $_{6}ψ_{6}$ summation formula

Lucy Slater used Bailey's $_6ψ_6$ summation formula to derive the Bailey pairs she used to construct her famous list of 130 identities of the Rogers-Ramanujan type. In the present paper we apply the same techniques to Chu's $_{10}ψ_{10}$ generalization of Bailey's formula to produce quite general Bailey pairs. Slater's Bailey pairs are then recovered as special limiting cases of these more general pairs. In re-examining Slater's work, we find that her Bailey pairs are, for the most part, special cases of more general Bailey pairs containing one or more free parameters. Further, we also find ne…

A Purely Algebraic Summation Method

It is mathematical folklore that 1 + 2 + 3 + 4 + ... = --1/12. This result is usually achieved using elaborate analytical methods, such as zeta function regularization or Ramanujan summation. However, in its notebooks, Ramanujan has also provided a very simple derivation which relied instead on algebraic manipulations. Recently, a video from Numberphile has presented a similar derivation of the result (provoking lots of discussions and debates about the meaning of such an equality). But this derivation, simple as it is, is usually considered as less rigorous than those using more elaborate ana…

Analogues of the general theta transformation formula

A new class of integrals involving the confluent hypergeometric function ${}_1F_{1}(a;c;z)$ and the Riemann $Ξ$-function is considered. It generalizes a class containing some integrals of S. Ramanujan, G.H. Hardy and W.L. Ferrar and gives as by-products, transformation formulas of the form $F(z,α)=F(iz,β)$, where $αβ=1$. As particular examples, we derive an extended version of the general theta transformation formula and generalizations of certain formulas of Ferrar and Hardy. A one-variable generalization of a well-known identity of Ramanujan is also given. We conclude with a generalization o…

Beyond Endoscopy via the trace formula - II: Asymptotic expansions of Fourier transforms and bounds towards the Ramanujan conjecture

We continue the analysis of the elliptic part of the trace formula initiated in \cite{Altug:2015aa}. In that reference Poisson summation was applied to the elliptic part and the dominant term was analyzed. The main aim of this paper is to study the remaining terms after Poisson summation. We analyze the the Fourier transforms of (smoothed) orbital integrals and obtain exact asymptotic expansions. As an application we recover, using the Arthur-Selberg trace formula, Kuznetsov's result (cf. \cite{Kuznetsov:1980aa}) that the trace of the $p$th Hecke operator on cuspidal automorphic representation…

Multiplicative Ramanujan coefficients of null-function

The null-function $0(a):=0$, $\forall a\in $N, has Ramanujan expansions: $0(a)=\sum_{q=1}^{\infty}(1/q)c_q(a)$ (where $c_q(a):=$ Ramanujan sum), given by Ramanujan, and $0(a)=\sum_{q=1}^{\infty}(1/φ(q))c_q(a)$, given by Hardy ($φ:=$ Euler's totient function). Both converge pointwise (not absolutely) in N. A $G:$N $\rightarrow $C is called a Ramanujan coefficient, abbrev. R.c., iff (if and only if) $\sum_{q=1}^{\infty}G(q)c_q(a)$ converges in all $a\in $N; given $F:$N $\rightarrow $C, we call $<F>$, the set of its R.c.s, the Ramanujan cloud of $F$. Our Main Theorem in arxiv:1910.14640, for Rama…

Voronoi求和公式、Riesz和的振荡，以及Ramanujan-Guinand型与Cohen型恒等式

Voronoi summation formulas, oscillations of Riesz sums, and Ramanujan-Guinand and Cohen type identities

本研究推导了刘维尔函数、莫比乌斯函数及除数函数平方的Voronoi求和公式，得到多类恒等式特例，并在相关数论猜想假设下证明了对应Riesz和及其误差项的振荡性质。

Ramanujan展开的光滑求和

A smooth summation of Ramanujan expansions

本文提出Ramanujan级数的光滑求和概念，证明其在Wintner假设下收敛，并应用于相关性与Hardy–Littlewood孪生素数猜想。

两平方数之和与tau函数：拉马努金的足迹

Sums of two squares and the tau-function: Ramanujan's trail

本文为综述，梳理了拉马努金在两平方数和计数、tau函数素数不可整除性方面的论断，补充相关历史细节并介绍后续进展，展现其在数论领域的探索性贡献。

Applications of Lipschitz summation formula and a generalization of Raabe's cosine transform

General summation formulas have been proved to be very useful in analysis, number theory and other branches of mathematics. The Lipschitz summation formula is one of them. In this paper, we give its application by providing a new transformation formula which generalizes that of Ramanujan. Ramanujan's result, in turn, is a generalization of the modular transformation of Eisenstein series $E_k(z)$ on SL$_2(\mathbb{Z})$, where $z\to-1/z, z\in\mathbb{H}$. The proof of our result involves delicate analysis containing Cauchy Principal Value integrals. A simpler proof of a recent result of ours with …

涉及二重、三重和四重和的Rogers-Ramanujan型恒等式

Rogers-Ramanujan type identities involving double, triple and quadruple sums

本文使用Maple搜索发现了多个涉及二重、三重和四重和的Rogers-Ramanujan型恒等式，并通过直接求和或常数项法将其转化为已知恒等式进行证明，同时得出新的单重和恒等式。

环面链环的多重 Rogers--Ramanujan 型恒等式

Multiple Rogers--Ramanujan type identities for torus links

本文为 $(2,2k)$ 环面链环的 Quot 和 motivic Cohen--Lenstra zeta 函数建立 $k$ 重求和表达式，导出多重 Rogers--Ramanujan 型恒等式并证实 Huang--Jiang 猜想。

整数划分函数渐近展开的简单误差界

Simple error bounds for an asymptotic expansion of the partition function

本文为整数划分函数 $p(n)$ 的 Poincaré 型简化渐近展开建立了可计算的误差界，该界比近期文献更尖锐且推导更简单。

Character analogues of certain Hardy-Berndt sums

In this paper we consider transformation formulas for \[ B\left( z,s:χ\right) =\sum\limits_{m=1}^{\infty}\sum\limits_{n=0} ^{\infty}χ(m)χ(2n+1)\left( 2n+1\right) ^{s-1}e^{πim(2n+1)z/k}. \] We derive reciprocity theorems for the sums arising in these transformation formulas and investigate certain properties of them. With the help of the character analogues of the Euler--Maclaurin summation formula we establish integral representations for the Hardy-Berndt character sums $s_{3,p}\left( d,c:χ\right) $ and $s_{4,p}\left( d,c:χ\right) $.

超分拆函数的高效计算及其应用

Efficient computation of the overpartition function and applications

本研究提出基于Hardy-Rademacher-Ramanujan型公式的超分拆函数高效计算方法，并用其发现了大量Treneer预测存在的新Ramanujan型同余式，补充了相关领域的已知结果。

A Partition Function Connected with the Göllnitz--Gordon Identities

We use the celebrated circle method of Hardy and Ramanujan to develop convergent formulae for counting a restricted class of partitions that arise from the Göllnitz--Gordon identities.

Complementary Schur Asymptotics for Partitions

We deduce from the strong form of the Hardy--Ramanujan asymptotics for the partition function $p(n)$ an asymptotics for $p_{-S}(n)$, the number of partitions of $n$ that do not use parts from a finite set $S$ of positive integers. We apply this to construct highly oscillating partition ideals.

Hybrid subconvexity and the partition function

We give an upper bound for the error term in the Hardy-Ramanujan-Rademacher formula for the partition function. The main input is a new hybrid subconvexity bound for the central value $L(\tfrac 12,f\times (\tfrac{q}{\cdot}))$ in the $q$ and spectral parameter aspects, where $f$ is a Hecke-Maass cusp form for $Γ_0(N)$ and $q$ is a fundamental discriminant.

关于埃尔多斯和拉马努金除数和的求和

On divisor sums due to Erdős and Ramanujan

本文研究了埃尔多斯和拉马努金除数和的混合形式，通过结合戈尔本的估计和塔兰的定量化形式，证明了除数和的渐进行为。

A modular relation involving non-trivial zeros of the Dedekind zeta function, and the Generalized Riemann Hypothesis

We give a number field analogue of a result of Ramanujan, Hardy and Littlewood, thereby obtaining a modular relation involving the non-trivial zeros of the Dedekind zeta function. We also provide a Riesz-type criterion for the Generalized Riemann Hypothesis for $ζ_K(s)$. New elegant transformations are obtained when $K$ is a quadratic extension, one of which involves the modified Bessel function of the second kind.

Towards an automation of the circle method

The derivation of the Hardy-Ramanujan-Rademacher formula for the number of partitions of $n$ is reviewed. Next, the steps for finding analogous formulas for certain restricted classes of partitions or overpartiitons is examined, bearing in mind how these calculations can be automated in a CAS. Finally, a number of new formulas of this type which were conjectured with the aid of \emph{Mathematica} are presented along with results of a test for their numerical accuracy.