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

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =2a(6) =4a(7) =6a(8) =10a(9) =17a(10) =27a(11) =44a(12) =72a(13) =116a(14) =188a(15) =305a(16) =493a(17) =798a(18) =1292a(19) =2090a(20) =3382a(21) =5473a(22) =8855a(23) =14328a(24) =23184a(25) =37512a(26) =60696a(27) =98209a(28) =158905a(29) =257114