A187006 A diagonal of triangle A187005.

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

Offset

1,2

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.

Links

Table of n, a(n) for n=1..18.

Prog

 (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)}

Crossrefs

Cf. A187005, A135081, A187007, A187008, A187009.

Sequence in context: A260578 A296792 A241462 * A321961 A088957 A030538

Adjacent sequences: A187003 A187004 A187005 * A187007 A187008 A187009

Keyword

nonn

Author

Paul D. Hanna, Mar 02 2011

Status

approved