OFFSET
0,5
FORMULA
T(n,k) = f(T(n-1,k-1)) + f(T(n-1,k))where f(n) = n*(n+1)/2 = A000217(n); T(0;0) = 1 ; T(n,k) = 0 if k<0 or if k>n.
EXAMPLE
Triangle begins:
1;
1, 1;
1, 2, 1;
1, 4, 4, 1;
1, 11, 20, 11, 1;
1, 67, 276, 276, 67, 1;
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Philippe Deléham, Jun 14 2006
STATUS
approved