Numbers of the form (6^{mr}-1)/(6^r-1) for positive integers m, r.

Terms

a(0) =1a(1) =7a(2) =37a(3) =43a(4) =217a(5) =259a(6) =1297a(7) =1333a(8) =1555a(9) =7777a(10) =9331a(11) =46657a(12) =46873a(13) =47989a(14) =55987a(15) =279937a(16) =335923a(17) =1679617a(18) =1680913a(19) =1727605a(20) =2015539a(21) =10077697a(22) =10124569a(23) =12093235a(24) =60466177a(25) =60473953a(26) =62193781a(27) =72559411a(28) =362797057a(29) =435356467