Numbers k such that k concatenated with k+7 is a prime.

Terms

a(0) =2a(1) =6a(2) =20a(3) =26a(4) =30a(5) =36a(6) =44a(7) =60a(8) =62a(9) =66a(10) =74a(11) =80a(12) =86a(13) =1004a(14) =1034a(15) =1046a(16) =1086a(17) =1094a(18) =1104a(19) =1136a(20) =1142a(21) =1194a(22) =1200a(23) =1206a(24) =1214a(25) =1224a(26) =1250a(27) =1262a(28) =1266a(29) =1290