Spiral sieve using Fibonacci numbers.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =7a(5) =17a(6) =25a(7) =40a(8) =63a(9) =99a(10) =156a(11) =249a(12) =397a(13) =538a(14) =1019a(15) =1637a(16) =2434a(17) =3989a(18) =6847a(19) =10634a(20) =17845a(21) =28827a(22) =46584a(23) =75299a(24) =121741a(25) =196862a(26) =318375a(27) =514947a(28) =832952a(29) =1347429