a(n) = 2*a(n-1) + 11*a(n-2) for n > 1, a(0) = a(1) = 1.

Terms

a(0) =1a(1) =1a(2) =13a(3) =37a(4) =217a(5) =841a(6) =4069a(7) =17389a(8) =79537a(9) =350353a(10) =1575613a(11) =7005109a(12) =31341961a(13) =139740121a(14) =624241813a(15) =2785624957a(16) =12437909857a(17) =55517694241a(18) =247852396909