OFFSET
0,3
COMMENTS
A skewed version of the Riordan array (1/(1-2x-x^2), x/(1-2x-x^2)), see A054456. - Philippe Deléham, Nov 21 2007
Triangle, read by rows, given by [0,1/2,-1/2,0,0,0,0,0,...] DELTA [2,1/2,-1/2,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Jan 30 2010
FORMULA
G.f.: 1/(1-2xy(1+x/2)-x^2*y^2);
T(n, k) = Sum_{j=0..floor((2k-n)/2)} C(k-j, n-k)*C(2k-n, j)*2^(2k-2j-n)};
T(n, k) = 2*T(n-1, k-1) + T(n-2, k-1) + T(n-2, k-2).
EXAMPLE
Rows begin
1;
0, 2;
0, 1, 5;
0, 0, 4, 12;
0, 0, 1, 14, 29;
0, 0, 0, 6, 44, 70;
0, 0, 0, 1, 27, 131, 169;
0, 0, 0, 0, 8, 104, 376, 408;
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Oct 05 2005
STATUS
approved