T(n,0) + T(n,1) + ... + T(n,n), T given by A026681.

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =26a(5) =54a(6) =120a(7) =276a(8) =606a(9) =1288a(10) =2852a(11) =6484a(12) =14256a(13) =30542a(14) =67568a(15) =152806a(16) =336154a(17) =723272a(18) =1599350a(19) =3605454a(20) =7934180a(21) =17118882a(22) =37843218a(23) =85124418a(24) =187367718a(25) =405074498a(26) =895273414a(27) =2010559668a(28) =4426193834