Position of n-th 5 in A031067.

Terms

a(0) =4a(1) =8a(2) =10a(3) =22a(4) =24a(5) =38a(6) =39a(7) =47a(8) =49a(9) =51a(10) =52a(11) =54a(12) =61a(13) =81a(14) =82a(15) =86a(16) =89a(17) =94a(18) =96a(19) =101a(20) =105a(21) =111a(22) =113a(23) =116a(24) =119a(25) =127a(26) =129a(27) =137a(28) =155a(29) =171