a(n) = 1 if a(n-1) is prime, otherwise a(n-1) + a(n-2), with a(0) = 0 and a(1) = 1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =1a(5) =3a(6) =1a(7) =4a(8) =5a(9) =1a(10) =6a(11) =7a(12) =1a(13) =8a(14) =9a(15) =17a(16) =1a(17) =18a(18) =19a(19) =1a(20) =20a(21) =21a(22) =41a(23) =1a(24) =42a(25) =43a(26) =1a(27) =44a(28) =45a(29) =89