A135083 - OEIS

A135083

Column 2 of triangle A135080.

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

(list; graph; refs; listen; history; text; internal format)

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