OFFSET
0,5
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..448
FORMULA
a(n) ~ n! * (-1)^(n+1) / (2*cosh(1)). - Vaclav Kotesovec, Jan 23 2015
MATHEMATICA
CoefficientList[Series[(x*(2 + x)*Sech[x])/(2*(1 + x)), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)
With[{nmax = 50}, CoefficientList[Series[Sinh[Log[1 + x]]/Cosh[x], {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, jan 21 2018 *)
PROG
(PARI) x='x+O('x^30); concat([0], Vec(serlaplace(sinh(log(1+x))/cosh(x)) )) \\ G. C. Greubel, Jan 21 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved