Self-convolution of array T given by A026648.

Terms

a(0) =1a(1) =2a(2) =11a(3) =34a(4) =138a(5) =492a(6) =2342a(7) =8500a(8) =39814a(9) =148124a(10) =709266a(11) =2665932a(12) =12824196a(13) =48623448a(14) =235400988a(15) =897705096a(16) =4362689862a(17) =16713200556a(18) =81488683874a(19) =313281535180