Composite numbers k such that 2^(2^(k-1)-1) == 1 (mod k^2).

Terms

a(0) =4681a(1) =15841a(2) =42799a(3) =52633a(4) =220729a(5) =647089a(6) =951481a(7) =1082401a(8) =1145257a(9) =1969417a(10) =2215441a(11) =3567481a(12) =4835209a(13) =5049001a(14) =5681809a(15) =6140161a(16) =6334351a(17) =8725753a(18) =10712857a(19) =11777599a(20) =12327121a(21) =13500313a(22) =14709241a(23) =22564081a(24) =22849481a(25) =22953673a(26) =23828017a(27) =27271151a(28) =28758601a(29) =30576151