Inserting any digit between adjacent digits of prime p produces exactly 1 new prime.

Terms

a(0) =101a(1) =149a(2) =163a(3) =241a(4) =269a(5) =271a(6) =317a(7) =347a(8) =367a(9) =397a(10) =409a(11) =419a(12) =443a(13) =487a(14) =509a(15) =541a(16) =587a(17) =601a(18) =641a(19) =761a(20) =787a(21) =811a(22) =821a(23) =863a(24) =907a(25) =919a(26) =1439a(27) =1481a(28) =1663a(29) =1877