Position of n-th 5 in A031018.

Terms

a(0) =3a(1) =17a(2) =31a(3) =32a(4) =34a(5) =36a(6) =38a(7) =45a(8) =66a(9) =87a(10) =101a(11) =104a(12) =107a(13) =108a(14) =129a(15) =150a(16) =171a(17) =173a(18) =176a(19) =179a(20) =182a(21) =192a(22) =213a(23) =234a(24) =248a(25) =251a(26) =254a(27) =255a(28) =276a(29) =297