OFFSET
0,5
FORMULA
G.f.: A(x, y) = 1/(1-(1+y)*x-y*x^2-(1+y)*x^3).
EXAMPLE
Generated by adding preceding terms in the triangle
at positions that form the letter 'C': T(n,k) =
T(n-3,k-1) + T(n-3,k) +
T(n-2,k-1) +
T(n-1,k-1) + T(n-1,k).
Rows begin:
[1],
[1,1],
[1,3,1],
[2,6,5,1],
[3,11,15,7,1],
[4,20,36,28,9,1],
[6,35,78,85,45,11,1],
[9,59,159,221,166,66,13,1],
[13,98,309,522,509,287,91,15,1],
[19,161,579,1153,1382,1018,456,120,17,1],...
PROG
(PARI) {T(n, k)=if(n<k||k<0, 0, if(n==0, 1, T(n-1, k)+T(n-1, k-1)+T(n-2, k-1)+T(n-3, k-1)+T(n-3, k)))}
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Paul D. Hanna, Dec 24 2004
STATUS
approved