Index of n-th 2 in A006928.

Terms

a(0) =2a(1) =5a(2) =7a(3) =8a(4) =10a(5) =11a(6) =14a(7) =17a(8) =18a(9) =20a(10) =23a(11) =25a(12) =26a(13) =29a(14) =32a(15) =34a(16) =35a(17) =37a(18) =38a(19) =41a(20) =43a(21) =44a(22) =46a(23) =49a(24) =52a(25) =53a(26) =55a(27) =56a(28) =59a(29) =61