A009597 Expansion of sinh(sinh(log(1+x))).

0, 1, -1, 4, -18, 106, -750, 6196, -58408, 617716, -7234020, 92842696, -1294948776, 19493497024, -314874396928, 5430592728016, -99578626460160, 1934092698170896, -39660351268817808, 856128235903319296

Offset

0,4

Links

G. C. Greubel, Table of n, a(n) for n = 0..440

Formula

a(n) ~ n! * (-1)^(n+1) * exp(1/4 + sqrt(2*n)) / (2^(9/4) * n^(3/4) * sqrt(Pi)). - Vaclav Kotesovec, Jan 24 2015

Mathematica

Sinh[ Sinh[ Log[ 1+x ] ] ]
CoefficientList[Series[Sinh[(x*(2 + x))/(2*(1 + x))], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)

Prog

(PARI) x='x+O('x^50); concat([0], Vec(serlaplace(sinh(sinh(log(1+x)))))) \\ G. C. Greubel, Apr 11 2017

Crossrefs

Sequence in context: A321278 A020114 A354015 * A241841 A241842 A306003

Adjacent sequences: A009594 A009595 A009596 * A009598 A009599 A009600

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved