A187122 A diagonal of triangle A187120.

1, 9, 81, 855, 10758, 159633, 2750067, 54178485, 1204443432, 29871630837, 818490738402, 24571782872034, 802459134168208, 28332664539686670, 1075700621922471621, 43710289920461797346, 1893011243289589171122

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 cube of triangle A135080.

Prog

 (PARI) {a(n)=local(Rn=y^3); for(m=3, n+1, Rn=subst(truncate(Rn), y, y+y^2+O(y^m))); polcoeff(Rn, n, y)}

Crossrefs

Cf. A187120, A135083, A187121, A187123, A187124.

Sequence in context: A077486 A233021 A366273 * A113361 A180737 A068881

Adjacent sequences: A187119 A187120 A187121 * A187123 A187124 A187125

Keyword

nonn

Author

Paul D. Hanna, Mar 08 2011

Status

approved