A187121 A diagonal of triangle A187120.

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

Offset

3,2

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.

Links

Table of n, a(n) for n=3..19.

Formula

Equals column 2 in the matrix square of triangle A135080.

Prog

(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)}

Crossrefs

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

Sequence in context: A368321 A052589 A074107 * A225497 A336950 A304071

Adjacent sequences: A187118 A187119 A187120 * A187122 A187123 A187124

Keyword

nonn

Author

Paul D. Hanna, Mar 08 2011

Status

approved