Numbers n such that 2^(sigma(n)-n) == 1 (mod n).

Terms

a(0) =1a(1) =511a(2) =713a(3) =11023a(4) =15553a(5) =43873a(6) =81079a(7) =323593a(8) =27923663a(9) =125093857a(10) =466572127a(11) =1108378657a(12) =2214217703a(13) =2871002911a(14) =3501195817a(15) =4107455887a(16) =4609840831a(17) =5066719081a(18) =5488711231a(19) =6331291231a(20) =9396536737