OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..45
FORMULA
a(n) = A191490(2*n,n).
MATHEMATICA
f[n_, k_] := f[n, k] = f[n - 1, k] + (n - 1)f[n - 1, k - 1] + If[n == k, 1, 0]
f[_, 0] = 1;
f[0, _] = 0;
Table[f[2n, n], {n, 0, 100}]
PROG
(Maxima) P[0]:1$
P[n]:=(1+(n-1)*q)*P[n-1]+q^n$
makelist(coeff(expand(P[2*n]), q^n), n, 0, 12);
CROSSREFS
KEYWORD
nonn
AUTHOR
Emanuele Munarini, Jun 03 2011
STATUS
approved