On Louchard's Asymptotic Series

Abstract

Recently G. Louchard obtained an asymptotic series $\sum_{j=0}^\infty\frac{I_j}{n^j}$ for the integral $\int_0^1[x^n+(1-x)^n]^{\frac1n}dx$ as $n\to\infty$, and computed $I_j$ for $j\le 5$ in terms of values of the Riemann zeta function. An interesting feature of the computation is that the $I_j$ are first obtained in terms of alternating multiple zeta values, but then everything except products of ordinary zeta values cancels out. We obtain similar formulas for $I_n$, $6\le n\le 9$, and conjecture a general formula for $I_n$ in terms of alternating multiple zeta values. We also conjecture that $I_n$ is a rational polynomial in the ordinary zeta values.

The conjectures made in the first version of this note were incorrect, due to neglect of some terms in the expansion of the integral