OFFSET
0,2
COMMENTS
FORMULA
G.f.: A(x, y) = 1/(1-x*y) + x*(x+2)/((1-x*y)^2*(1+x+x*y)^2).
EXAMPLE
Triangle begins:
1;
2,1;
-3,0,1;
4,4,4,1;
-5,-10,-10,0,1;
6,18,24,12,6,1;
-7,-28,-49,-42,-21,0,1;
8,40,88,104,72,24,8,1;
-9,-54,-144,-216,-198,-108,-36,0,1;
10,70,220,400,460,340,160,40,10,1; ...
PROG
(PARI) {T(n, k)=local(x=X+X*O(X^n), y=Y+Y*O(Y^k)); polcoeff(polcoeff(1/(1-x*y)+x*(x+2)/((1-x*y)^2*(1+x+x*y)^2), n, X), k, Y)}
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Paul D. Hanna, Oct 23 2005
STATUS
approved