Primes that are concatenations of k-th prime and k-th composite.

Terms

a(0) =79a(1) =5927a(2) =7333a(3) =10139a(4) =14951a(5) =22769a(6) =443117a(7) =541133a(8) =593143a(9) =727169a(10) =739171a(11) =941207a(12) =1103237a(13) =1213253a(14) =1367279a(15) =1447291a(16) =1511303a(17) =1553309a(18) =1667329a(19) =2011381a(20) =2129399a(21) =2213411a(22) =2237413a(23) =2267417a(24) =2287423a(25) =2339429a(26) =2609471