A187121 A diagonal of triangle A187120.

1, 6, 42, 377, 4248, 58269, 947117, 17848872, 383237040, 9243654925, 247586590398, 7293962774574, 234458181733224, 8167132024738422, 306500617604837898, 12329458457556027538, 529269910501209999900

Offset: 3

Author

Paul D. Hanna, Mar 08 2011

Keywords

• nonn

Comments

Definition of triangle: A187120(n,k) = [y^k] R_{n-1}(y+y^2) for k=3..n, n>3, where R_n(y) is the n-th row polynomial starting with R_3(y)=y^3.

Crossrefs

Cf. A187120, A135083, A187122, A187123, A187124.

Programs

PARI

{a(n)=local(Rn=y^3);for(m=3,n,Rn=subst(truncate(Rn),y,y+y^2+O(y^m)));polcoeff(Rn,n,y)}

Formula

Equals column 2 in the matrix square of triangle A135080.