Position of n-th 7 in A031045.

Terms

a(0) =7a(1) =22a(2) =38a(3) =54a(4) =70a(5) =86a(6) =102a(7) =105a(8) =107a(9) =109a(10) =111a(11) =113a(12) =115a(13) =117a(14) =118a(15) =119a(16) =141a(17) =165a(18) =189a(19) =213a(20) =237a(21) =261a(22) =285a(23) =289a(24) =292a(25) =295a(26) =298a(27) =301a(28) =304a(29) =307