OFFSET
0,2
COMMENTS
Asymptotic expansion (below) converge much faster if n is odd. If n is even, then more than 1000 terms necessary for right numerical verification. - Vaclav Kotesovec, Nov 01 2013
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..200
Vaclav Kotesovec, graph a(n) / asymptotic
FORMULA
E.g.f.: (x+sqrt(1+x^2))*exp(tanh(x)). - Vaclav Kotesovec, Nov 01 2013
a(n) ~ -2*cos(Pi*n/2-tan(1)) * n^(n-1) / exp(n). - Vaclav Kotesovec, Nov 01 2013
MATHEMATICA
CoefficientList[Series[Exp[Tanh[x]+ArcSinh[x]], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Nov 01 2013 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved