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

Terms

a(0) =991a(1) =99119a(2) =191911a(3) =911111a(4) =919111a(5) =999199a(6) =1911911a(7) =1991911a(8) =9111911a(9) =11911111a(10) =19911191a(11) =19919111a(12) =19991911a(13) =99111119a(14) =911111191a(15) =991111111a(16) =991991111a(17) =999199991a(18) =999919919a(19) =1911119911a(20) =1919991191a(21) =1991111911a(22) =1991919191