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A107718
Column 1 of triangle A107717.
1
1, 6, 57, 723, 11361, 212151, 4584081, 112480887, 3090105921, 93988998183, 3136338148017, 113945190405303, 4477940877230625, 189296643095867847, 8565988634172222609, 413169192012610306263, 21161884092470464784385
OFFSET
0,2
COMMENTS
Equals one-half of column 0 of A107719 shift 1 place left.
PROG
(PARI) {a(n)=if(n<0, 0, (matrix(n+2, n+2, m, j, if(m>=j, if(m==j, 1, if(m==j+1, -3*j, polcoeff(1/sum(i=0, m-j, prod(r=0, i-1, 3*r+1)*x^i)+O(x^m), m-j)))))^-1)[n+2, 2])}
CROSSREFS
Sequence in context: A152170 A087659 A369071 * A308863 A000406 A305276
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 30 2005
STATUS
approved