login
A187007
A diagonal of triangle A187005.
5
1, 3, 12, 69, 538, 5404, 67092, 997581, 17337444, 345547750, 7778860028, 195365725310, 5418540898800, 164556820433116, 5432639292242576, 193765826638479112, 7426524928340527902, 304439910637309354106
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.
PROG
(PARI) {a(n)=local(Rn=y); for(m=1, n+2, Rn=subst(truncate(Rn), y, y+y^2+y*O(y^m))); polcoeff(Rn, n, y)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 02 2011
STATUS
approved