Primes that are a concatenation of 2*k and 2*k+1 or 2*k and 2*k-1 for some k.

Terms

a(0) =23a(1) =43a(2) =67a(3) =89a(4) =109a(5) =1213a(6) =2221a(7) =2423a(8) =3433a(9) =3637a(10) =4241a(11) =4243a(12) =5051a(13) =5657a(14) =5857a(15) =6263a(16) =6869a(17) =7069a(18) =7877a(19) =7879a(20) =8081a(21) =8887a(22) =9091a(23) =9293a(24) =9697a(25) =10099a(26) =102101a(27) =102103a(28) =108107a(29) =108109