Numbers k such that k surrounded by digit '1' is a prime.

Terms

a(0) =0a(1) =3a(2) =5a(3) =8a(4) =9a(5) =15a(6) =17a(7) =18a(8) =20a(9) =23a(10) =29a(11) =30a(12) =32a(13) =36a(14) =38a(15) =45a(16) =47a(17) =48a(18) =51a(19) =53a(20) =57a(21) =60a(22) =62a(23) =72a(24) =74a(25) =80a(26) =81a(27) =83a(28) =86a(29) =87