Composite numbers k such that 2^k == 1 (mod cototient(k)).

Terms

a(0) =15a(1) =143a(2) =869a(3) =16727a(4) =17017a(5) =26791a(6) =31135a(7) =32399a(8) =36863a(9) =57599a(10) =58609a(11) =63145a(12) =65535a(13) =106327a(14) =124241a(15) =137863a(16) =176399a(17) =186623a(18) =206111a(19) =416111a(20) =435599a(21) =546407a(22) =571097a(23) =788839a(24) =1040399a(25) =1065023a(26) =1101047a(27) =1240001a(28) =1301189a(29) =1665799