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

Terms

a(0) =1a(1) =80519a(2) =107663a(3) =1284113a(4) =1510313a(5) =3933023a(6) =4557713a(7) =24849833a(8) =71871113a(9) =80646143a(10) =98058097a(11) =104832833a(12) =106694033a(13) =146987033a(14) =168204191a(15) =188997463a(16) =205428713a(17) =332693873a(18) =333681761a(19) =336327863a(20) =380284847a(21) =533039513a(22) =552913169a(23) =711999113a(24) =725943719a(25) =805031663a(26) =1000519033a(27) =1069441313a(28) =1476327353a(29) =1610020913