Numbers k such that k prefixed by '2' and followed by '3' is prime.

Terms

a(0) =2a(1) =3a(2) =6a(3) =8a(4) =9a(5) =11a(6) =14a(7) =15a(8) =20a(9) =21a(10) =24a(11) =27a(12) =29a(13) =33a(14) =38a(15) =39a(16) =42a(17) =47a(18) =50a(19) =54a(20) =59a(21) =63a(22) =66a(23) =68a(24) =69a(25) =71a(26) =75a(27) =80a(28) =83a(29) =84