A187007 A diagonal of triangle A187005.

1, 3, 12, 69, 538, 5404, 67092, 997581, 17337444, 345547750, 7778860028, 195365725310, 5418540898800, 164556820433116, 5432639292242576, 193765826638479112, 7426524928340527902, 304439910637309354106

Offset

1,2

Comments

Definition of triangle: A187005(n,k) = [y^k] R_{n-1}(y+y^2) for k=1..n where R_n(y) is the n-th row polynomial for n>1 with R_1(y)=y.

Links

Table of n, a(n) for n=1..18.

Prog

 (PARI) {a(n)=local(Rn=y); for(m=1, n+2, Rn=subst(truncate(Rn), y, y+y^2+y*O(y^m))); polcoeff(Rn, n, y)}

Crossrefs

Cf. A187005, A135081, A187006, A187008, A187009.

Sequence in context: A375807 A144008 A244610 * A102078 A113341 A125862

Adjacent sequences: A187004 A187005 A187006 * A187008 A187009 A187010

Keyword

nonn

Author

Paul D. Hanna, Mar 02 2011

Status

approved