OFFSET
0,2
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
FORMULA
a(n) = Sum_{k>=0} binomial(2n+1, 2k)*A000111(2n+1-2k). - Philippe Deléham, Aug 27 2005
a(n) ~ cosh(Pi/2) * (2*n+1)! * 2^(2*n+3) / Pi^(2*n+2). - Vaclav Kotesovec, Feb 16 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[Cosh[x]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 16 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended and formatted Mar 15 1997 by Olivier Gérard
Prior Mathematica program deleted by Harvey P. Dale, Nov 04 2019
STATUS
approved