login
A113986
Column 3 of triangle A113983; also a(n) = A113983(n+2,2) + [A113983^2](n+1,2).
4
1, 4, 13, 43, 153, 603, 2657, 13111, 72273, 443147, 3007077, 22462571, 183744033, 1637653579, 15828157233, 165167123583, 1853228997585, 22274643111107, 285799117829549, 3902028545084315, 56522214876304249, 866295289106559595
OFFSET
0,2
FORMULA
a(n) = [A113983^3](n, 0) + [A113983^4](n-1, 0) = A113994(n) + A113995(n-1).
PROG
(PARI) a(n)=local(A, B); A=Mat(1); for(m=2, n+4, B=matrix(m, m); for(i=1, m, for(j=1, i, if(i<3 || j==1 || j==i, B[i, j]=1, B[i, j]=A[i-1, j-1]+(A^2)[i-2, j-1]); )); A=B); A[n+4, 4]
CROSSREFS
Cf. A113983, A113984 (column 1), A113985 (column 2), A113987 (column 4).
Sequence in context: A033434 A297928 A363366 * A149426 A042767 A286175
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 12 2005
STATUS
approved