A166904 Row sums of triangle A166900.

1, 2, 7, 40, 321, 3361, 43667, 679806, 12358885, 257281501, 6039232167, 157879127902, 4550258562799, 143367509714352, 4903128661348411, 180907738215049666, 7163333648262397913, 303006716530386750233

Offset: 0

Author

Paul D. Hanna, Nov 27 2009

Keywords

• nonn

Comments

Triangle A166900 transforms rows into diagonals in the table of coefficients of successive iterations of x+x^2 (cf. A122888).

Crossrefs

Cf. A166900, A166901, A166902, A166903, A122888, A135080.

Programs

PARI

{a(n)=local(F=x, M, N, P); M=matrix(n+2, n+2, r, c, F=x;for(i=1, r+c-2, F=subst(F, x, x+x^2+x*O(x^(n+2)))); polcoeff(F, c)); N=matrix(n+1, n+1, r, c, F=x;for(i=1, r, F=subst(F, x, x+x^2+x*O(x^(n+3)))); polcoeff(F, c)); P=matrix(n+1, n+1, r, c, M[r+1, c]); M=(P~*N~^-1); sum(k=1,n+1,M[n+1,k])}