This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A087538 #12 Sep 20 2024 23:54:22 %S A087538 89,88989899,98988899,98989889,99898889,8889899899,8889988999, %T A087538 8889998899,8898988999,8898989989,8899889989,8988998899,8988999889, %U A087538 8989889899,8989889989,8989899889,8989988899,8998998889,8999888899,9888899899,9888989899,9889898899,9889988989 %N A087538 Primes consisting only of digits 8 and 9 occurring with equal frequency. %C A087538 There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9). %H A087538 Andrew Howroyd, <a href="/A087538/b087538.txt">Table of n, a(n) for n = 1..5275</a> %o A087538 (PARI) \\ Needs B() from A087510. %o A087538 concat(vector(6,k,B(k,8,9,isprime))) \\ _Andrew Howroyd_, Sep 20 2024 %Y A087538 Cf. A087510, A087511, A087537. %K A087538 base,nonn %O A087538 1,1 %A A087538 _Amarnath Murthy_ and _Paul D. Hanna_, Sep 12 2003 %E A087538 Edited by _Charles R Greathouse IV_, Oct 28 2009 %E A087538 Offset changed and a(20) onwards from _Andrew Howroyd_, Sep 20 2024