Self-convolution of array T given by A026637.

Terms

a(0) =1a(1) =2a(2) =6a(3) =34a(4) =116a(5) =438a(6) =1606a(7) =6002a(8) =22548a(9) =85342a(10) =324716a(11) =1241166a(12) =4762000a(13) =18329054a(14) =70742790a(15) =273689362a(16) =1061055812a(17) =4121135838a(18) =16032654628a(19) =62463904958a(20) =243682621224a(21) =951781620022