Integer nearest nx, where x = sqrt(5).

Terms

a(0) =0a(1) =2a(2) =4a(3) =7a(4) =9a(5) =11a(6) =13a(7) =16a(8) =18a(9) =20a(10) =22a(11) =25a(12) =27a(13) =29a(14) =31a(15) =34a(16) =36a(17) =38a(18) =40a(19) =42a(20) =45a(21) =47a(22) =49a(23) =51a(24) =54a(25) =56a(26) =58a(27) =60a(28) =63a(29) =65