a(n) = ceiling(exp((n-1)/2)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =8a(6) =13a(7) =21a(8) =34a(9) =55a(10) =91a(11) =149a(12) =245a(13) =404a(14) =666a(15) =1097a(16) =1809a(17) =2981a(18) =4915a(19) =8104a(20) =13360a(21) =22027a(22) =36316a(23) =59875a(24) =98716a(25) =162755a(26) =268338a(27) =442414a(28) =729417a(29) =1202605