Numbers k such that k divides 2^(2k+1) + 1.

Terms

a(0) =1a(1) =3a(2) =129a(3) =2537a(4) =51889a(5) =101617a(6) =226873a(7) =270427a(8) =653467a(9) =945667a(10) =1740979a(11) =5819937a(12) =6520987a(13) =9828587a(14) =15452867a(15) =24950857a(16) =51377539a(17) =89519449a(18) =108627601a(19) =135776371a(20) =160126609a(21) =296338873a(22) =310026163a(23) =400431289a(24) =641706243a(25) =643359937a(26) =678257563a(27) =803419697a(28) =902661523a(29) =952431331