Lesser of emirps (pairs) with digits 1 and 9 only.

Terms

a(0) =199a(1) =91199a(2) =111119a(3) =111919a(4) =119191a(5) =991999a(6) =1191119a(7) =1191191a(8) =1191991a(9) =11111911a(10) =11191991a(11) =11919991a(12) =19111991a(13) =91111199a(14) =111111199a(15) =111199199a(16) =191111119a(17) =199991999a(18) =919919999a(19) =1111111999a(20) =1191111991a(21) =1199111191a(22) =1911199999