Duplicate of A055500.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =11a(7) =17a(8) =23a(9) =37a(10) =59a(11) =89a(12) =139a(13) =227a(14) =359a(15) =577a(16) =929a(17) =1499a(18) =2423a(19) =3919a(20) =6337