A135082 Column 1 of triangle A135080.

1, 2, 7, 40, 326, 3492, 46558, 744320, 13889080, 296459376, 7125938790, 190502850972, 5607258255032, 180198503713952, 6278311585490032, 235730921392184452, 9489040823468191328, 407662178549724426176

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

Crossrefs

Cf. A135080 (triangle); other columns: A135081, A135083.

Sequence in context: A166904 A105625 A367255 * A102317 A361828 A031973

Adjacent sequences: A135079 A135080 A135081 * A135083 A135084 A135085

Keyword

nonn

Author

Paul D. Hanna, Nov 18 2007

Status

approved