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 A263431 #9 Mar 29 2020 19:13:07
%S A263431 89,8999,98999,99989,989999,9899999,89999999,99899999,99998999,
%T A263431 99999989,998999999,98999999999,99989999999,999998999999,999999999899,
%U A263431 999999999989,99899999999999,99999899999999,99999999899999,999999899999999,999999999989999,999999999999989
%N A263431 Near-repdigit primes with only digits 9 and a single 8 in decimal expansion.
%H A263431 Felix Fröhlich, <a href="/A263431/b263431.txt">Table of n, a(n) for n = 1..200</a>
%t A263431 Select[Flatten[Table[FromDigits/@Permutations[PadRight[{8},n,9]],{n,15}]],PrimeQ] (* _Harvey P. Dale_, Mar 29 2020 *)
%o A263431 (PARI) a002283(n) = 10^n-1
%o A263431 a011557(n) = 10^n
%o A263431 num(n, k) = a002283(n)-a011557(k)
%o A263431 terms(n) = i=0; x=1; while(x > 0, y=x-1; while(y >= 0, if(ispseudoprime(num(x, y)), print1(num(x, y), ", "); i++); if(i==n, break({2})); y--); x++)
%o A263431 terms(30) \\ print initial thirty terms
%Y A263431 Cf. A020472, A065074, A069661, A105975, A178007.
%K A263431 nonn,base,easy
%O A263431 1,1
%A A263431 _Felix Fröhlich_, Oct 18 2015