Composite numbers k such that b^k == b (mod sigma(k)) for every integer b.

Terms

a(0) =7381a(1) =13357a(2) =18421a(3) =69121a(4) =70021a(5) =129961a(6) =192589a(7) =241501a(8) =271921a(9) =313501a(10) =342793a(11) =399421a(12) =423613a(13) =625681a(14) =780913a(15) =1265641a(16) =1362097a(17) =1501489a(18) =1566181a(19) =1673101a(20) =1691521a(21) =1728001a(22) =2228941a(23) =2381401a(24) =2472301a(25) =2642221a(26) =3156661a(27) =3171961a(28) =3383281a(29) =3557521