A135083 Column 2 of triangle A135080.

1, 3, 15, 112, 1128, 14373, 221952, 4029915, 84135510, 1985740905, 52277994396, 1518768476508, 48261093246396, 1665034362336120, 61979166611850084, 2475861386988907814, 105641851808320785498, 4795101548183135826810

Offset

0,2

Comments

Triangle A135080 transforms diagonals in the table of coefficients of successive self-compositions 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+4, n+4, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x+x^2+x*O(x^(n+4)))); polcoeff(F, c)); N=matrix(n+3, n+3, r, c, M[r, c]); P=matrix(n+3, n+3, r, c, M[r+1, c]); (P~*N~^-1)[n+3, 3]}

Crossrefs

Cf. A135080 (triangle); other columns: A135081, A135082.

Sequence in context: A130168 A267083 A089945 * A323772 A058104 A298390

Adjacent sequences: A135080 A135081 A135082 * A135084 A135085 A135086

Keyword

nonn

Author

Paul D. Hanna, Nov 18 2007

Status

approved