A108477 A symmetric number triangle based on 2^n.
1, 1, 1, 1, 13, 1, 1, 41, 41, 1, 1, 85, 321, 85, 1, 1, 145, 1289, 1289, 145, 1, 1, 221, 3649, 8989, 3649, 221, 1, 1, 313, 8361, 40081, 40081, 8361, 313, 1, 1, 421, 16641, 134245, 265729, 134245, 16641, 421, 1, 1, 545, 29961, 369305, 1256465, 1256465, 369305, 29961, 545, 1
Offset: 0
Examples
Rows begin 1; 1, 1; 1, 13, 1; 1, 41, 41, 1; 1, 85, 321, 85, 1; 1, 145, 1289, 1289, 145, 1;
Formula
T(n,k) = Sum_{j=0..n} C(2(n-k), j) * C(2k, j) * 2^j if 0<=k<=n otherwise 0.