OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..100
FORMULA
E.g.f.: B(x)^3/6 where B(x) is e.g.f. for A144636. [From Vladeta Jovovic, Jan 24 2009]
MAPLE
A:= proc(n, k) option remember; if n=k then 1 elif k<n or n<1 then 0 else A(n-1, k-1) +(k-1) *A(n-1, k-2) +(k-1) *(k-2) *A(n-1, k-3)/2 fi end: M:= proc(n) option remember; Matrix(n+1, (i, j)-> A(i-1, j-1))^(-1) end: a:= n-> M (n+3)[4, n+1]: seq (a(n), n=0..25); # Alois P. Heinz, Oct 25 2009
MATHEMATICA
max = 22; t[n_, n_] = 1; t[n_ /; n >= 0, k_] /; (0 <= k <= 3*n) := t[n, k] = t[n-1, k-1] + (k-1)*t[n-1, k-2] + (1/2)*(k-1)*(k-2)*t[n-1, k-3]; t[_, _] = 0; A144633 = Table[t[n, k], {n, 0, max}, {k, 0, max}] // Inverse // Transpose ; A144633[[All, 4]] (* Jean-François Alcover, Jan 17 2014 *)
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Jan 23 2009
EXTENSIONS
More terms from Alois P. Heinz, Oct 25 2009
STATUS
approved