OFFSET
0,5
COMMENTS
FORMULA
Number triangle T(n,k)=sum{j=0..n, C(n,j)*if(k<=j, C(j-1,2j-2k)*A000108(j-k),0)}; G.f.: 1/(1-x-x(1-x)y/(1-x/(1-xy/(1-x/(1-xy/(1-... (continued fraction).
EXAMPLE
Triangle begins
1,
1, 1,
1, 2, 1,
1, 3, 4, 1,
1, 4, 10, 7, 1,
1, 5, 20, 27, 11, 1,
1, 6, 35, 77, 61, 16, 1,
1, 7, 56, 182, 236, 121, 22, 1,
1, 8, 84, 378, 726, 611, 218, 29, 1,
1, 9, 120, 714, 1902, 2375, 1394, 365, 37, 1
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Jul 11 2009
STATUS
approved