a(n) = self-convolution of row n of array T given by A026747.

Terms

a(0) =1a(1) =2a(2) =11a(3) =34a(4) =183a(5) =630a(6) =3384a(7) =12192a(8) =65536a(9) =242232a(10) =1303758a(11) =4900880a(12) =26415708a(13) =100525392a(14) =542639986a(15) =2084879028a(16) =11271483340a(17) =43645729836a(18) =236329734438a(19) =921177944356