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 A050625 #11 Apr 04 2020 20:52:02
%S A050625 3,6,9,18,27,36,45,54,63,72,81,90,99,108,135,162,189,216,243,270,297,
%T A050625 324,351,378,405,432,459,486,513,540,567,594,621,648,675,702,729,756,
%U A050625 783,810,837,864,891,918,945,972,999,1053,1134,1215,1296,1377,1458
%N A050625 Divisible by 3^k (where k is digit length of a(n)).
%H A050625 Harvey P. Dale, <a href="/A050625/b050625.txt">Table of n, a(n) for n = 1..1000</a>
%t A050625 Flatten[Table[3^n*Range[Ceiling[10^(n-1)/3^n],Floor[(10^n-1)/3^n]],{n,4}]] (* _Harvey P. Dale_, Feb 26 2015 *)
%t A050625 Select[Range[1500],Mod[#,3^IntegerLength[#]]==0&] (* _Harvey P. Dale_, Apr 04 2020 *)
%Y A050625 Cf. A035014, A050622, A050623.
%K A050625 nonn,base,easy
%O A050625 1,1
%A A050625 _Patrick De Geest_, Jun 15 1999