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 A066557 #10 Dec 06 2024 20:20:26
%S A066557 9,98,999,9996,99995,999996,9999997,99999992,999999999,9999999990,
%T A066557 99999999990,999999999996,9999999999990,99999999999998,
%U A066557 999999999999990,9999999999999984,99999999999999990,999999999999999990,9999999999999999990,99999999999999999980
%N A066557 Largest n-digit multiple of n.
%H A066557 Harry J. Smith, <a href="/A066557/b066557.txt">Table of n, a(n) for n = 1..150</a>
%F A066557 a(n) = floor((10^n-1)/n)*n.
%o A066557 (PARI) a(n) = { (10^n - 1)\n*n } \\ _Harry J. Smith_, Feb 22 2010
%Y A066557 Cf. A053041, A066558.
%K A066557 nonn,base
%O A066557 1,1
%A A066557 _Amarnath Murthy_, Dec 17 2001
%E A066557 More terms and formula from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 24 2001