a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A027144.

Terms

a(0) =1a(1) =3a(2) =7a(3) =21a(4) =45a(5) =135a(6) =291a(7) =873a(8) =1881a(9) =5643a(10) =12159a(11) =36477a(12) =78597a(13) =235791a(14) =508059a(15) =1524177a(16) =3284145a(17) =9852435a(18) =21229047a(19) =63687141a(20) =137226717a(21) =411680151a(22) =887047443a(23) =2661142329a(24) =5733964809a(25) =17201894427a(26) =37064931183a(27) =111194793549a(28) =239591481525a(29) =718774444575