Position of n-th 7 in A031324.

Terms

a(0) =23a(1) =24a(2) =30a(3) =34a(4) =44a(5) =53a(6) =54a(7) =61a(8) =67a(9) =86a(10) =111a(11) =121a(12) =124a(13) =129a(14) =133a(15) =149a(16) =152a(17) =189a(18) =204a(19) =205a(20) =211a(21) =222a(22) =236a(23) =242a(24) =247a(25) =252a(26) =254a(27) =255a(28) =256a(29) =258