Primes formed by the concatenation k, k-2, k.

Terms

a(0) =313a(1) =757a(2) =131113a(3) =171517a(4) =312931a(5) =393739a(6) =474547a(7) =494749a(8) =575557a(9) =939193a(10) =111109111a(11) =127125127a(12) =139137139a(13) =147145147a(14) =151149151a(15) =169167169a(16) =189187189a(17) =213211213a(18) =217215217a(19) =227225227a(20) =237235237a(21) =239237239a(22) =247245247a(23) =253251253a(24) =269267269a(25) =331329331a(26) =333331333a(27) =353351353a(28) =363361363a(29) =377375377