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 A014884 #10 Dec 02 2020 09:42:14 %S A014884 1,102772,102773,102774,102775,102776,102777,102778,102779,102780, %T A014884 142155,142156,737002,737003,737004,737005,737006,737007,737008, %U A014884 737009,737010,1594323,1594324,1697095,1697096,1697097,1697098 %N A014884 n is equal to the number of 1's in all numbers <= n written in base 9. %H A014884 Robert Israel, <a href="/A014884/b014884.txt">Table of n, a(n) for n = 1..49</a> %p A014884 T:= 0: R:= NULL: %p A014884 for n from 1 to 6*10^6 do %p A014884 T:= T + numboccur(1,convert(n,base,9)); %p A014884 if T = n then R:= R, n fi %p A014884 od: %p A014884 R; # _Robert Israel_, Dec 01 2020 %Y A014884 Cf. A014778. %K A014884 nonn,base,fini,full %O A014884 1,2 %A A014884 _Olivier Gérard_