Numbers of the form (8^{mr}-1)/(8^r-1) for positive integers m, r.

Terms

a(0) =1a(1) =9a(2) =65a(3) =73a(4) =513a(5) =585a(6) =4097a(7) =4161a(8) =4681a(9) =32769a(10) =37449a(11) =262145a(12) =262657a(13) =266305a(14) =299593a(15) =2097153a(16) =2396745a(17) =16777217a(18) =16781313a(19) =17043521a(20) =19173961a(21) =134217729a(22) =134480385a(23) =153391689a(24) =1073741825a(25) =1073774593a(26) =1090785345a(27) =1227133513a(28) =8589934593a(29) =9817068105