A187007 A diagonal of triangle A187005.

1, 3, 12, 69, 538, 5404, 67092, 997581, 17337444, 345547750, 7778860028, 195365725310, 5418540898800, 164556820433116, 5432639292242576, 193765826638479112, 7426524928340527902, 304439910637309354106, 13293321078232321952036, 616016966059346344408690, 30196821383142448481822800

Offset: 1

Author

Paul D. Hanna, Mar 02 2011

Keywords

• nonn

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.

Crossrefs

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

Programs

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)}

Extensions

More terms from Michel Marcus, Feb 01 2025