Position of n-th 2 in A031018.

Terms

a(0) =7a(1) =12a(2) =14a(3) =16a(4) =21a(5) =35a(6) =51a(7) =68a(8) =71a(9) =72a(10) =74a(11) =77a(12) =93a(13) =114a(14) =121a(15) =124a(16) =127a(17) =130a(18) =133a(19) =135a(20) =136a(21) =139a(22) =142a(23) =143a(24) =145a(25) =146a(26) =148a(27) =149a(28) =151a(29) =154