OFFSET
0,9
FORMULA
G.f.: 1/((1-x*y)*(1-x^2*y)*(1-x^3*y^2)); Number triangle T(n, k)=sum{j=0..k, [j<=n-k]*[j<=2k-n]}; T(n, k)=A003983(k, n-k).
EXAMPLE
Triangle begins
1;
0,1;
0,1,1;
0,0,2,1;
0,0,1,2,1;
0,0,0,2,2,1;
0,0,0,1,3,2,1;
0,0,0,0,2,3,2,1;
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Jan 19 2006
STATUS
approved