a(n) = 3^n*A228569(n).

Terms

a(0) =2a(1) =15a(2) =171a(3) =2160a(4) =27783a(5) =358425a(6) =4626234a(7) =59716035a(8) =770832207a(9) =9950150160a(10) =128439782811