Primes that are concatenations of n with n + 3.

Terms

a(0) =47a(1) =811a(2) =1013a(3) =1619a(4) =4447a(5) =4649a(6) =5659a(7) =5861a(8) =6871a(9) =7477a(10) =8689a(11) =9497a(12) =98101a(13) =100103a(14) =104107a(15) =106109a(16) =136139a(17) =140143a(18) =148151a(19) =154157a(20) =158161a(21) =160163a(22) =166169a(23) =176179a(24) =184187a(25) =194197a(26) =206209a(27) =230233a(28) =244247a(29) =250253