Emirps with digits 1 and 9 only.

Terms

a(0) =199a(1) =991a(2) =91199a(3) =99119a(4) =111119a(5) =111919a(6) =119191a(7) =191911a(8) =911111a(9) =919111a(10) =991999a(11) =999199a(12) =1191119a(13) =1191191a(14) =1191991a(15) =1911911a(16) =1991911a(17) =9111911a(18) =11111911a(19) =11191991a(20) =11911111a(21) =11919991a(22) =19111991a(23) =19911191a(24) =19919111a(25) =19991911