A166893 Column 3 of triangle A166890.

1, 6, 63, 986, 20685, 545736, 17365336, 647216568, 27653205177, 1332422277828, 71470510481961, 4223498675806638, 272615162534575302, 19082609490868539738, 1439738711122827542742, 116468234559061615308870

Offset

1,2

Comments

Triangle A166890 transforms diagonals in the triangle A166888 of coefficients in the successive iterations of x*(1+x)^2.

Links

Table of n, a(n) for n=1..16.

Prog

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

Crossrefs

Cf. A166890, A166891, A166892.

Sequence in context: A295267 A098342 A107995 * A213644 A280476 A295241

Adjacent sequences: A166890 A166891 A166892 * A166894 A166895 A166896

Keyword

nonn

Author

Paul D. Hanna, Nov 22 2009

Status

approved