OFFSET
0,2
EXAMPLE
Triangle A113993 begins:
1;
1,1;
1,2,1;
1,4,3,1;
1,8,9,4,1;
1,18,27,16,5,1;
1,46,89,64,25,6,1;
1,136,327,276,125,36,7,1;
1,464,1353,1304,665,216,49,8,1; ...
PROG
(PARI) a(n)=local(A, B); A=Mat(1); for(m=2, n+2, 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); sum(k=0, n, (A^(k+1))[n-k+1, 1])
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 12 2005
STATUS
approved