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 A087513 #14 Sep 21 2024 12:44:02
%S A087513 61,16166611,16616161,61116661,61661161,66161611,1166116661,
%T A087513 1166166161,1166166611,1166616161,1616616611,1661116661,6111166661,
%U A087513 6111666611,6116116661,6161161661,6161166161,6161166611,6161661161,6166111661,6166161161,6611616611,6616161161,6616161611
%N A087513 Primes consisting only of digits 1 and 6 occurring with equal frequency.
%C A087513 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 A087513 Andrew Howroyd, <a href="/A087513/b087513.txt">Table of n, a(n) for n = 1..5201</a> (first 5001 terms from Harvey P. Dale)
%t A087513 Table[Select[FromDigits/@Permutations[PadRight[{},2*n,{1,6}]],PrimeQ],{n,5}]//Flatten//Sort (* _Harvey P. Dale_, May 28 2019 *)
%o A087513 (PARI) \\ Needs B() from A087510.
%o A087513 concat(vector(6,k,B(k,1,6,isprime))) \\ _Andrew Howroyd_, Sep 21 2024
%Y A087513 Cf. A087510, A087511, A087512.
%K A087513 base,nonn
%O A087513 1,1
%A A087513 _Amarnath Murthy_ and _Paul D. Hanna_, Sep 11 2003
%E A087513 Offset changed by _Andrew Howroyd_, Sep 21 2024