a(n) = 3^(2*n-1) + 2.

Terms

a(0) =5a(1) =29a(2) =245a(3) =2189a(4) =19685a(5) =177149a(6) =1594325a(7) =14348909a(8) =129140165a(9) =1162261469a(10) =10460353205a(11) =94143178829a(12) =847288609445