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arXiv 0810.1354math.NT
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区间内的除数与欧拉-马歇罗尼常数

Divisors in windows and the Euler--Mascheroni constant

University of New Hampshire(新罕布什尔大学)

David Victor Feldman

AI总结:

该数学研究推导了区间内除数个数的平均值公式,涉及欧拉-马歇罗尼常数等,结果在Lean 4中得到形式化验证。

摘要:

对于0<c<1,当q≤B时,q的小于q^c的除数个数的平均值为c log B + (γ - c) + O(B^{-min(c,1-c)}),其中γ表示欧拉-马歇罗尼常数。因此,区间(q^a, q^b)内的除数个数的平均值为(b-a)(log B -1) + o(1):常数γ被抵消,两个区间的平均值在渐近上与区间的指数长度之比相关。特别地,一个数在(n^{1/4},n^{1/2)内的除数平均数是在(n^{1/8},n^{1/4)内的两倍,该论证完全未提及γ。将区间锚定在阈值及其平方根处会使对数抵消:对于弱递增函数F,满足F(q)→∞且q/F(q)→∞,数q在小于√F(q)的区间内的除数平均数比在[√F(q),F(q))区间内多恰好γ个。对于以q本身为尺度的区间,其平均值取决于端点约定:当α∈(0,1)时,统计小于√(α q)的除数与在(√(α q),α q)内的除数,得到平均值为H_{⌊1/α⌋} - log(1/α);而区间(√(α q),α q]的平均值为H_{⌈1/α⌉-1} - log(1/α);当1/α为整数时,两个常数恰好相差α。α的任一函数均在γ附近振荡,当α→0时趋于γ,且在(0,1)上的积分值为ζ(2)-1。主要结果在Lean 4中得到形式化验证。

英文摘要:

For $0<c<1$ the number of divisors of $q$ below $q^{c}$ averages, over $q\le B$, to $c\log B+(γ-c)+O(B^{-\min(c,1-c)})$, where $γ$ denotes the Euler--Mascheroni constant. Consequently the number of divisors in a window $(q^{a},q^{b})$ averages to $(b-a)(\log B-1)+o(1)$: the constant $γ$ cancels, and the average counts for two windows stand asymptotically in the ratio of the windows' exponent lengths. In particular a number has, on average, twice as many divisors in $(n^{1/4},n^{1/2})$ as in $(n^{1/8},n^{1/4})$, by an argument nowhere mentioning $γ$. Anchoring a window at a threshold and its square root makes the logarithms cancel instead: for weakly increasing $F$ with $F(q)\to\infty$ and $q/F(q)\to\infty$, a number $q$ has, on average, exactly $γ$ more divisors below $\sqrt{F(q)}$ than in $[\sqrt{F(q)},F(q))$. For windows on the scale of $q$ itself the average depends on an endpoint convention: with $α\in(0,1)$, counting divisors below $\sqrt{αq}$ against divisors in $(\sqrt{αq},αq)$ yields the average $H_{\lfloor 1/α\rfloor}-\log(1/α)$, while the window $(\sqrt{αq},αq]$ yields $H_{\lceil 1/α\rceil-1}-\log(1/α)$; the two constants differ exactly when $1/α$ takes an integer value, and then by $α$. Either function of $α$ oscillates about $γ$, tends to $γ$ as $α\to0$, and integrates over $(0,1)$ to $ζ(2)-1$. The principal results are formally verified in Lean~4.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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