Composite Flavius' numbers (A000960) whose prime factors are again Flavius' numbers.

Terms

a(0) =27a(1) =39a(2) =49a(3) =63a(4) =91a(5) =133a(6) =147a(7) =399a(8) =567a(9) =763a(10) =2187a(11) =13239a(12) =15379a(13) =15883a(14) =21207a(15) =32761a(16) =151599a(17) =173563a(18) =180739a(19) =268423a(20) =746607a(21) =2277163a(22) =2557359a(23) =3114783a(24) =8218083a(25) =28604419a(26) =65002743a(27) =68944959a(28) =91727883a(29) =93742347