Consecutive prime pairs which after concatenation are prime (ascending or descending order).

Terms

a(0) =23a(1) =53a(2) =3137a(3) =5347a(4) =5953a(5) =6761a(6) =8389a(7) =137131a(8) =151157a(9) =157163a(10) =167173a(11) =179173a(12) =199211a(13) =211199a(14) =223211a(15) =233239a(16) =239233a(17) =257263a(18) =263257a(19) =263269a(20) =271277a(21) =331337a(22) =353359a(23) =359353a(24) =373379a(25) =433439a(26) =467479a(27) =509521a(28) =523541a(29) =541523