OFFSET
0,2
COMMENTS
PROG
(PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+2, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(A^i)[i-1, j]); )); A=B); return((A^3)[n+2, 2])}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Aug 23 2006
EXTENSIONS
Edited by N. J. A. Sloane, Oct 30 2008 at the suggestion of R. J. Mathar
STATUS
approved