OFFSET
0,2
COMMENTS
Row sums are the powers of 3.
FORMULA
G.f.: (1+2*x-y*x)/(1-2*y*x-(2+y)*x^2).
T(n,k) = 2*T(n-1,k-1) + 2*T(n-2,k) + T(n-2,k-1), T(0,0) = T(1,1) = 1, T(1,0) = T(2,0) = T(2,2) = 2, T(2,1) = 5 and T(n,k) = 0 if k<0 or if k>n.
EXAMPLE
Triangle begins :
1
2, 1
2, 5, 2
4, 8, 11, 4
4, 20, 25, 24, 8
8, 28, 70, 69, 52, 16
8, 60, 126, 213, 178, 112, 32
16, 80, 288, 460, 599, 440, 240, 64
16, 160, 472, 1128, 1489, 1600, 1056, 512, 128
32, 208, 976, 2152, 3914, 4457, 4120, 2480, 1088, 256
CROSSREFS
KEYWORD
AUTHOR
Philippe Deléham, Apr 28 2012
STATUS
approved