a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A027170.

Terms

a(0) =1a(1) =6a(2) =20a(3) =52a(4) =120a(5) =260a(6) =544a(7) =1116a(8) =2264a(9) =4564a(10) =9168a(11) =18380a(12) =36808a(13) =73668a(14) =147392a(15) =294844a(16) =589752a(17) =1179572a(18) =2359216a(19) =4718508a(20) =9437096a(21) =18874276a(22) =37748640a(23) =75497372a(24) =150994840a(25) =301989780a(26) =603979664a(27) =1207959436a(28) =2415918984