a(n) = 3^n + 2.

Terms

a(0) =3a(1) =5a(2) =11a(3) =29a(4) =83a(5) =245a(6) =731a(7) =2189a(8) =6563a(9) =19685a(10) =59051a(11) =177149a(12) =531443a(13) =1594325a(14) =4782971a(15) =14348909a(16) =43046723a(17) =129140165a(18) =387420491a(19) =1162261469a(20) =3486784403a(21) =10460353205a(22) =31381059611a(23) =94143178829a(24) =282429536483a(25) =847288609445