A109156 Row sums of triangle A109152.

1, 2, 5, 14, 47, 188, 867, 4460, 25025, 150890, 967825, 6554482, 46600855, 346228012, 2677951311, 21495038944, 178565654041, 1531692226714, 13538763090277, 123096619532030, 1149440819867767, 11007471611129700

Offset

0,2

Comments

Triangular matrix T=A109152 satisfies: T(n,k) = [T^2](n-1,k) for n>k+1>=1, with T(n,n) = 1 and T(n+1,n) = n+1 for n>=0.

Links

Table of n, a(n) for n=0..21.

Prog

(PARI) {a(n)=local(M=matrix(n+1, n+1)); M=M^0; for(i=1, n, M=matrix(n+1, n+1, r, c, if(r>=c, if(r==c, 1, if(r==c+1, c, (M^2)[r-1, c]))))); return(sum(k=0, n, M[n+1, k+1]))}

Crossrefs

Cf. A109152 (triangle), A109153 (column 0), A109154 (column 1), A109155 (column 2).

Sequence in context: A096402 A007268 A326898 * A143918 A129867 A119841

Adjacent sequences: A109153 A109154 A109155 * A109157 A109158 A109159

Keyword

nonn

Author

Paul D. Hanna, Jun 20 2005

Status

approved