OFFSET
1,3
COMMENTS
With changed signs, expansion of e.g.f. tanh(arcsin(x)).
LINKS
Muniru A Asiru, Table of n, a(n) for n = 1..60
FORMULA
a(n) ~ (-1)^(n+1) * 2^(2*n) * n^(2*n-2) / ((cosh(Pi)+1)*exp(2*n)). - Vaclav Kotesovec, Oct 23 2013
EXAMPLE
tan(arcsinh(x)) = x + x^3/3! + 5x^5/5! + 5x^7/7! + 1865x^9/9! - ...
MAPLE
seq(coeff(series(factorial(n)*tan(arcsinh(x)), x, n+1), x, n), n=1..30, 2); # Muniru A Asiru, Jul 22 2018
MATHEMATICA
Table[n!*SeriesCoefficient[Tan[ArcSinh[x]], {x, 0, n}], {n, 1, 40, 2}] (* Vaclav Kotesovec, Oct 23 2013 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Ralf Stephan, Dec 28 2004
STATUS
approved