Numbers k such that 2^(4*k-1) == 1 (mod k).

Terms

a(0) =1a(1) =7a(2) =511a(3) =10033a(4) =242959a(5) =1265839a(6) =1838599a(7) =4138729a(8) =4446631a(9) =10561159a(10) =13179319a(11) =19926007a(12) =21224239a(13) =38356159a(14) =65746249a(15) =72161239a(16) =82180303a(17) =87563239a(18) =88323689a(19) =98352799a(20) =124563313a(21) =153394537a(22) =158525689a(23) =219011569a(24) =248520769a(25) =348485359a(26) =498260329a(27) =636381799a(28) =638395369a(29) =685333399