OFFSET
0,2
FORMULA
a(n) ~ 2^(2*n) * n^(2*n) * r^(2*n+1) / (sqrt(2-r) * exp(2*n) * (1-r)^(n+1/2)), where r = 2/(2+LambertW(2*exp(-2))) = 0.901829091937052... . - Vaclav Kotesovec, May 14 2014
MATHEMATICA
Table[Sum[Binomial[n, k]*(2*k+1)^(2*n), {k, 0, n}], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vaclav Kotesovec, May 12 2014
STATUS
approved