Positions of odd numbers in A004432.

Terms

a(0) =2a(1) =4a(2) =6a(3) =8a(4) =10a(5) =12a(6) =14a(7) =17a(8) =18a(9) =20a(10) =22a(11) =25a(12) =26a(13) =28a(14) =29a(15) =32a(16) =34a(17) =35a(18) =38a(19) =40a(20) =42a(21) =43a(22) =45a(23) =47a(24) =49a(25) =52a(26) =54a(27) =56a(28) =57a(29) =58