A009401 Expansion of e.g.f. log(1+tanh(x)/cosh(x)).

0, 1, -1, -3, 14, -15, -136, 1197, -5776, -255, 420224, -5448003, 30166784, 241437105, -8354415616, 104019879597, -291139373056, -17849464279935, 456381834297344, -5108933510880003, -26967886768439296, 2525823613297136625, -55703951522570960896, 425245839735677809197

Offset

0,4

Links

Table of n, a(n) for n=0..23.

Mathematica

CoefficientList[Series[Log[1+Tanh[x]/Cosh[x]], {x, 0, 23}], x]*Range[0, 23]! (* Stefano Spezia, Oct 17 2025 *)

Crossrefs

Sequence in context: A303222 A037244 A016062 * A195864 A394048 A349767

Adjacent sequences: A009398 A009399 A009400 * A009402 A009403 A009404

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

a(22)-a(23) from Stefano Spezia, Oct 17 2025

Status

approved