A166907 Column 2 of triangle A166905.

1, 9, 108, 1610, 28560, 586320, 13658904, 355787568, 10243342296, 322939137312, 11063339361360, 409194048521778, 16249995494795920, 689585033717023224, 31140529927119263136, 1490994828293677370148, 75444108490820383882392

Offset

0,2

Comments

Triangle A166905 transforms rows into diagonals in the table A158825 of coefficients in successive iterations of x*Catalan(x) (cf. A000108).

Links

Table of n, a(n) for n=0..16.

Prog

(PARI) {a(n)=local(F=x, G=serreverse(x-x^2+O(x^(n+5))), M, N, P, m=n); M=matrix(m+4, m+4, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, G+x*O(x^(m+4)))); polcoeff(F, c)); N=matrix(m+3, m+3, r, c, F=x; for(i=1, r, F=subst(F, x, G+x*O(x^(m+4)))); polcoeff(F, c)); P=matrix(m+3, m+3, r, c, M[r+1, c]); (P~*N~^-1)[n+3, 3]}

Crossrefs

Cf. A166905, A158831, A166906, A166908, A166909.

Sequence in context: A214668 A234467 A288550 * A051606 A330876 A001691

Adjacent sequences: A166904 A166905 A166906 * A166908 A166909 A166910

Keyword

nonn

Author

Paul D. Hanna, Nov 28 2009

Status

approved