OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..49
FORMULA
a(n) = sum_{k=0..n} A048993(2*k,k).
a(n+1)-a(n) = A007820(n+1).
a(n) ~ n^n * 2^(2*n) / (sqrt(2*Pi*(1-c)*n) * exp(n) * (2-c)^n * c^n), where c = -LambertW(-2*exp(-2)). - Vaclav Kotesovec, May 11 2014
MAPLE
seq(sum(combinat[stirling2](2*k, k), k=0..n), n=0..12);
MATHEMATICA
Table[Sum[StirlingS2[2k, k], {k, 0, n}], {n, 0, 16}]
PROG
(Maxima) makelist(sum(stirling2(2*k, k), k, 0, n), n, 0, 12);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emanuele Munarini, Mar 12 2011
STATUS
approved