OFFSET
0,3
COMMENTS
A transform of the Jacobsthal numbers.
a(2n)=A007583(n)=(2*4^n+1)/3.
MATHEMATICA
With[{nn=30}, CoefficientList[Series[(1/Cosh[x]+Tanh[x]) (Exp[2x]- Exp[-x])/3, {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Aug 22 2012 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Jan 21 2005
EXTENSIONS
Corrected by N. J. A. Sloane, Nov 05 2005
STATUS
approved