Position of n-th 2 in A031253.

Terms

a(0) =6a(1) =9a(2) =11a(3) =16a(4) =28a(5) =39a(6) =42a(7) =43a(8) =45a(9) =58a(10) =62a(11) =65a(12) =68a(13) =71a(14) =73a(15) =74a(16) =77a(17) =78a(18) =80a(19) =81a(20) =83a(21) =86a(22) =88a(23) =89a(24) =92a(25) =95a(26) =103a(27) =114a(28) =117a(29) =118