A187117 - OEIS

A187117

A diagonal of triangle A187115.

1, 6, 39, 318, 3242, 40348, 598083, 10337402, 204706486, 4577520108, 114208773268, 3147671423964, 95023271024164, 3119560618275648, 110684959354534001, 4221624141483353436, 172274971776090819870

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OFFSET

2,2

COMMENTS

Definition of triangle: A187115(n,k) = [y^k] R_{n-1}(y+y^2) for k=2..n, n>2, where R_n(y) is the n-th row polynomial with R_2(y)=y^2.

LINKS

Table of n, a(n) for n=2..18.

FORMULA

Equals column 1 in the matrix cube of triangle A135080.

PROG

(PARI) {a(n)=local(Rn=y^2); for(m=2, n+2, Rn=subst(truncate(Rn), y, y+y^2+O(y^m))); polcoeff(Rn, n, y)}

CROSSREFS

Cf. A187115, A135082, A187116, A187118, A187119.

Sequence in context: A335344 A135890 A067273 * A137972 A007322 A341728

Adjacent sequences: A187114 A187115 A187116 * A187118 A187119 A187120

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 08 2011

STATUS

approved