Primes with prime number of only prime digits (i.e., 2, 3, 5, 7).

Terms

a(0) =23a(1) =37a(2) =53a(3) =73a(4) =223a(5) =227a(6) =233a(7) =257a(8) =277a(9) =337a(10) =353a(11) =373a(12) =523a(13) =557a(14) =577a(15) =727a(16) =733a(17) =757a(18) =773a(19) =22273a(20) =22277a(21) =22573a(22) =22727a(23) =22777a(24) =23227a(25) =23327a(26) =23333a(27) =23357a(28) =23537a(29) =23557