Primes formed by the concatenation of exactly two consecutive composite numbers.

Terms

a(0) =89a(1) =5051a(2) =5657a(3) =6263a(4) =6869a(5) =8081a(6) =9091a(7) =9293a(8) =120121a(9) =186187a(10) =188189a(11) =200201a(12) =216217a(13) =242243a(14) =246247a(15) =252253a(16) =278279a(17) =300301a(18) =308309a(19) =318319a(20) =338339a(21) =342343a(22) =350351a(23) =362363a(24) =368369a(25) =390391a(26) =402403a(27) =410411a(28) =416417a(29) =426427