Position of n-th 5 in A031298.

Terms

a(0) =5a(1) =20a(2) =40a(3) =60a(4) =80a(5) =91a(6) =93a(7) =95a(8) =97a(9) =99a(10) =100a(11) =101a(12) =103a(13) =105a(14) =107a(15) =109a(16) =120a(17) =140a(18) =160a(19) =180a(20) =205a(21) =235a(22) =265a(23) =295a(24) =325a(25) =341a(26) =344a(27) =347a(28) =350a(29) =353