Earliest sequence with a(a(n))=5n.

Terms

a(0) =0a(1) =2a(2) =5a(3) =4a(4) =15a(5) =10a(6) =7a(7) =30a(8) =9a(9) =40a(10) =25a(11) =12a(12) =55a(13) =14a(14) =65a(15) =20a(16) =17a(17) =80a(18) =19a(19) =90a(20) =75a(21) =22a(22) =105a(23) =24a(24) =115a(25) =50a(26) =27a(27) =130a(28) =29a(29) =140