OFFSET
1,1
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..100
FORMULA
a(n) ~ (-1)^(n+1) * sinh(1) * 2^(2*n+2) * n^(2*n-1) / (exp(2*n) * (cosh(Pi*tanh(1)+1) + cosh(Pi*tanh(1)-1) + 2*cosh(1))). - Vaclav Kotesovec, Oct 30 2013
MAPLE
a:= n-> (2*n)! *coeff(series(tanh(arcsinh(x)*tan(x)), x, 2*n+2), x, 2*n):
seq (a(n), n=1..20); # Alois P. Heinz, Jul 11 2012
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[ArcSinh[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {3, -1, 2}]] (* Harvey P. Dale, Jul 11 2012 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Definition clarified by and more terms from Harvey P. Dale, Jul 11 2012
STATUS
approved