a(n) = ceiling(Fibonacci(n)/2).

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =4a(7) =7a(8) =11a(9) =17a(10) =28a(11) =45a(12) =72a(13) =117a(14) =189a(15) =305a(16) =494a(17) =799a(18) =1292a(19) =2091a(20) =3383a(21) =5473a(22) =8856a(23) =14329a(24) =23184a(25) =37513a(26) =60697a(27) =98209a(28) =158906a(29) =257115