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 A261512 #23 Mar 08 2023 05:13:28
%S A261512 9,99,997,9999,99987,999987,9999997,99999979,999999991,9999999997,
%T A261512 99999999973,999999999937,9999999999999,99999999999943,999999999999993
%N A261512 Largest n-digit lucky number.
%o A261512 (Perl) use ntheory ":all"; for (1..12) { $n=10**$_-1; $n-- while !is_lucky($n); say "$_ $n"; } # _Dana Jacobsen_, Mar 07 2023
%Y A261512 Cf. A000959, A003618.
%K A261512 nonn,base,more
%O A261512 1,1
%A A261512 _Robert G. Wilson v_, Aug 22 2015
%E A261512 a(11)-a(15) from _Hiroaki Yamanouchi_, Aug 24 2015