Powers of 3: a(n) = 3^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =27a(4) =81a(5) =243a(6) =729a(7) =2187a(8) =6561a(9) =19683a(10) =59049a(11) =177147a(12) =531441a(13) =1594323a(14) =4782969a(15) =14348907a(16) =43046721a(17) =129140163a(18) =387420489a(19) =1162261467a(20) =3486784401a(21) =10460353203a(22) =31381059609a(23) =94143178827a(24) =282429536481a(25) =847288609443