a(n) = (F(2*n-1) + F(n+1))/2 where F(n) is a Fibonacci number.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =51a(7) =127a(8) =322a(9) =826a(10) =2135a(11) =5545a(12) =14445a(13) =37701a(14) =98514a(15) =257608a(16) =673933a(17) =1763581a(18) =4615823a(19) =12082291a(20) =31628466a(21) =82798926a(22) =216761547a(23) =567474769a(24) =1485645049a(25) =3889431721a(26) =10182603746a(27) =26658304492a(28) =69792188337a(29) =182718064101