A009122 Expansion of e.g.f. cosh(log(1+log(1+x))).

1, 0, 1, -6, 41, -335, 3229, -36036, 457932, -6534384, 103499016, -1802302128, 34227784920, -704076488232, 15595687319640, -370108332316992, 9368461983616128, -251958336139856448, 7174771808983995456

Offset

0,4

Links

G. C. Greubel, Table of n, a(n) for n = 0..250

Formula

a(n) ~ n! * (-1)^n * exp(n) / (2 * (exp(1)-1)^(n+1)). - Vaclav Kotesovec, Jan 22 2015

Mathematica

CoefficientList[Series[(1 + (1 + Log[1 + x])^2)/(2*(1 + Log[1 + x])), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)

Prog

(PARI) x='x+O('x^30); Vec(serlaplace(cosh(log(1+log(1+x))))) \\ G. C. Greubel, Jul 26 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cosh(Log(1+Log(1+x))))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 26 2018

Crossrefs

Twice the absolute values are in A052864.

Sequence in context: A083430 A005011 A187814 * A184140 A317410 A094869

Adjacent sequences: A009119 A009120 A009121 * A009123 A009124 A009125

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved