Concatenation of 'prevprime(k) and k' is a prime.

Terms

a(0) =3a(1) =9a(2) =37a(3) =39a(4) =51a(5) =63a(6) =87a(7) =89a(8) =111a(9) =117a(10) =123a(11) =153a(12) =157a(13) =163a(14) =173a(15) =177a(16) =183a(17) =207a(18) =211a(19) =213a(20) =217a(21) =219a(22) =239a(23) =249a(24) =257a(25) =263a(26) =267a(27) =269a(28) =273a(29) =277