Integers of the form (2^x + 1) / (2^y + 1).

Terms

a(0) =1a(1) =3a(2) =11a(3) =13a(4) =43a(5) =57a(6) =171a(7) =205a(8) =241a(9) =683a(10) =993a(11) =2731a(12) =3277a(13) =3641a(14) =4033a(15) =10923a(16) =16257a(17) =43691a(18) =52429a(19) =61681a(20) =65281a(21) =174763a(22) =233017a(23) =261633a(24) =699051a(25) =838861a(26) =1016801a(27) =1047553a(28) =2796203a(29) =4192257