A187006 A diagonal of triangle A187005.

1, 2, 6, 29, 202, 1880, 22108, 315784, 5322126, 103541022, 2285965792, 56501970700, 1546339364952, 46433615292128, 1518172222889000, 53695946069029290, 2042960241832903824, 83207255745283689726, 3612360848988984098484, 166537270023045091100852, 8125771150231992039148508

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, A187007, A187008, A187009.

Programs

PARI

{a(n)=local(Rn=y);for(m=1,n+1,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