dorsal/arxiv
View SchemaOn the variance of the digits of $1/p$
| Authors | Kurt Girstmair |
|---|---|
| Categories | |
| ArXiv ID | 2601.08416vv1 |
| URL | https://arxiv.org/abs/2601.08416 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
Let $p>3$ be a prime and $b\ge 2$ an integer such that $p$ does not divide $b$. Then $1/p$ has a periodic digit expansion with respect to the basis $b$. The length $q$ of the period is the (multiplicative) order of $b$ mod $p$. In the case $q=p-1$ a formula for the variance of the digits of a period was given previously. This formula involves a Dedekind sum. We determine the variance in the case $q=(p-1)/2$. If $p\equiv 3$ mod 4 a Dedekind sum and the class number of $\mathbb Q(\sqrt{-p})$ occur in the respective formula. If $p\equiv 1$ mod 4, the formula may be much more complex since it involves linear combinations of (possibly many) products of two Bernoulli numbers attached to odd characters.
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"abstract": "Let $p\u003e3$ be a prime and $b\\ge 2$ an integer such that $p$ does not divide $b$. Then $1/p$ has a periodic digit expansion with respect to the basis $b$. The length $q$ of the period is the (multiplicative) order of $b$ mod $p$. In the case $q=p-1$ a formula for the variance of the digits of a period was given previously. This formula involves a Dedekind sum. We determine the variance in the case $q=(p-1)/2$. If $p\\equiv 3$ mod 4 a Dedekind sum and the class number of $\\mathbb Q(\\sqrt{-p})$ occur in the respective formula. If $p\\equiv 1$ mod 4, the formula may be much more complex since it involves linear combinations of (possibly many) products of two Bernoulli numbers attached to odd characters.",
"arxiv_id": "2601.08416",
"authors": [
"Kurt Girstmair"
],
"categories": [
"math.NT"
],
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "On the variance of the digits of $1/p$",
"url": "https://arxiv.org/abs/2601.08416",
"version": "v1"
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