Position of n-th 1 in A031269.

Terms

a(0) =1a(1) =4a(2) =6a(3) =11a(4) =12a(5) =13a(6) =16a(7) =21a(8) =25a(9) =27a(10) =37a(11) =50a(12) =52a(13) =53a(14) =56a(15) =57a(16) =69a(17) =70a(18) =73a(19) =76a(20) =77a(21) =81a(22) =82a(23) =95a(24) =98a(25) =102a(26) =110a(27) =111a(28) =116a(29) =121