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Fractional part integral representation for derivatives of a function related to ln Gamma(x+1)

Mathematical Physics 2011-08-24 v2 math.MP

Abstract

For 0x>10\neq x>-1 let Δ(x)=lnΓ(x+1)x.\Delta(x)={{\ln \Gamma(x+1)} \over x}. Recently Adell and Alzer proved the complete monotonicity of Δ\Delta' on (1,)(-1,\infty) by giving an integral representation of (1)nΔ(n+1)(x)(-1)^n \Delta^{(n+1)}(x) in terms of the Hurwitz zeta function ζ(s,a)\zeta(s,a). We reprove this integral representation in different ways, and then re-express it in terms of fractional part integrals. Special cases then have explicit evaluations. Other relations for Δ(n+1)(x)\Delta^{(n+1)}(x) are presented, including its leading asymptotic form as xx \to \infty.

Keywords

Cite

@article{arxiv.1101.4257,
  title  = {Fractional part integral representation for derivatives of a function related to ln Gamma(x+1)},
  author = {Mark W. Coffey},
  journal= {arXiv preprint arXiv:1101.4257},
  year   = {2011}
}

Comments

15 pages, no figures. Some new references. To appear in Publ. Math. Debrecen