Position of n-th 2 in A031219.

Terms

a(0) =2a(1) =10a(2) =15a(3) =17a(4) =19a(5) =20a(6) =21a(7) =23a(8) =30a(9) =40a(10) =53a(11) =68a(12) =76a(13) =79a(14) =82a(15) =83a(16) =85a(17) =88a(18) =98a(19) =113a(20) =120a(21) =123a(22) =126a(23) =128a(24) =129a(25) =132a(26) =135a(27) =138a(28) =141a(29) =143