Primes that remain prime through 2 iterations of function f(x) = 4x + 9.

Terms

a(0) =7a(1) =41a(2) =43a(3) =47a(4) =67a(5) =71a(6) =97a(7) =103a(8) =137a(9) =263a(10) =293a(11) =307a(12) =397a(13) =421a(14) =467a(15) =491a(16) =571a(17) =587a(18) =593a(19) =683a(20) =727a(21) =757a(22) =883a(23) =907a(24) =1021a(25) =1061a(26) =1063a(27) =1097a(28) =1153a(29) =1373