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

0,2

Comments

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

Links

Table of n, a(n) for n=0..17.

Prog

(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])}

Crossrefs

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

Sequence in context: A370878 A162653 A346220 * A105625 A367255 A135082

Adjacent sequences: A166901 A166902 A166903 * A166905 A166906 A166907

Keyword

nonn

Author

Paul D. Hanna, Nov 27 2009

Status

approved