Values of n for which the concatenations 1nn1, 3nn3, 7nn7 and 9nn9 are all primes.

Terms

a(0) =2092a(1) =2131a(2) =2797a(3) =3433a(4) =4126a(5) =5524a(6) =5710a(7) =6817a(8) =8383a(9) =8815a(10) =9472a(11) =114613a(12) =116329a(13) =130213a(14) =206776a(15) =239389a(16) =282298a(17) =286642a(18) =306046a(19) =307180a(20) =311317a(21) =318310a(22) =341386a(23) =360733a(24) =366529a(25) =377005a(26) =425665a(27) =430597a(28) =460441a(29) =475642