A166907 - OEIS

A166907

Column 2 of triangle A166905.

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

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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