Numbers k such that k^2 divides 8^k-1.

Terms

a(0) =1a(1) =7a(2) =889a(3) =2359a(4) =299593a(5) =2033143a(6) =13549249a(7) =42931441a(8) =100170217a(9) =310935751a(10) =685169191a(11) =3606045247a(12) =4566096913a(13) =5452293007a(14) =6620620783a(15) =12721617559a(16) =30987132463a(17) =65576560063a(18) =92349997537a(19) =104785348087a(20) =457967746369