Position of n-th 6 in A031312.

Terms

a(0) =56a(1) =58a(2) =60a(3) =62a(4) =64a(5) =187a(6) =190a(7) =193a(8) =196a(9) =199a(10) =337a(11) =340a(12) =343a(13) =346a(14) =349a(15) =487a(16) =490a(17) =493a(18) =496a(19) =499a(20) =637a(21) =640a(22) =643a(23) =646a(24) =649a(25) =787a(26) =790a(27) =793a(28) =796a(29) =799