Position of n-th 7 in A031035.

Terms

a(0) =7a(1) =23a(2) =39a(3) =55a(4) =71a(5) =87a(6) =103a(7) =104a(8) =106a(9) =108a(10) =110a(11) =112a(12) =114a(13) =116a(14) =118a(15) =119a(16) =143a(17) =167a(18) =191a(19) =215a(20) =239a(21) =263a(22) =287a(23) =289a(24) =292a(25) =295a(26) =298a(27) =301a(28) =304a(29) =307