Primes with consecutive digits that differ exactly by 4.

Terms

a(0) =2a(1) =3a(2) =5a(3) =7a(4) =37a(5) =59a(6) =73a(7) =151a(8) =373a(9) =15959a(10) =95959a(11) =515951a(12) =595159a(13) =595951a(14) =9515959a(15) =51515159a(16) =159595151a(17) =159595951a(18) =5151515951a(19) =5159515159a(20) =5159515951a(21) =5951515151a(22) =5951515951a(23) =5959515151a(24) =5959595951a(25) =15151595951a(26) =15951515159