Numbers k such that 2^(3^j) == 1 (mod k) for some j.

Terms

a(0) =1a(1) =7a(2) =73a(3) =487a(4) =511a(5) =2593a(6) =3409a(7) =18151a(8) =35551a(9) =39367a(10) =71119a(11) =80191a(12) =97687a(13) =189289a(14) =209953a(15) =248857a(16) =262657a(17) =275569a(18) =379081a(19) =472393a(20) =497833a(21) =561337a(22) =683809a(23) =1262791a(24) =1299079a(25) =1325023a(26) =1469671a(27) =1838599a(28) =2653567a(29) =2873791