Numbers k such that 2^(k*(k+1)/2) == -1 (mod k^2).

Terms

a(0) =1a(1) =389993a(2) =476729a(3) =2927297a(4) =3048569a(5) =3862529a(6) =3914049a(7) =4755729a(8) =5077209a(9) =7460409a(10) =9009489a(11) =9314009a(12) =11066649a(13) =11981409a(14) =12928289a(15) =13342769a(16) =15371609a(17) =15574449a(18) =22975249a(19) =34429449a(20) =44876649a(21) =57046209a(22) =66358417a(23) =66963369a(24) =79552209a(25) =83006769a(26) =96783929a(27) =99127313a(28) =118462737a(29) =126209609