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

Terms

a(0) =3a(1) =107a(2) =421a(3) =773a(4) =1567a(5) =1637a(6) =3793a(7) =4111a(8) =6961a(9) =12721a(10) =14107a(11) =17851a(12) =26267a(13) =26557a(14) =31327a(15) =33503a(16) =37003a(17) =42281a(18) =57947a(19) =60091a(20) =65423a(21) =67427a(22) =68447a(23) =75721a(24) =82223a(25) =82657a(26) =87877a(27) =96377a(28) =108107a(29) =111373