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 A001613 #8 Feb 01 2022 23:33:50
%S A001613 0,0,2,0,4,0,6,0,8,0,0,0,2,0,4,0,6,0,8,0,20,2,22,2,24,2,26,2,28,2,0,0,
%T A001613 2,0,4,0,6,0,8,0,40,4,42,4,44,4,46,4,48,4,0,0,2,0,4,0,6,0,8,0,60,6,62,
%U A001613 6,64,6,66,6,68,6,0,0,2,0,4,0,6,0,8,0,80,8
%N A001613 Delete all odd digits from n.
%H A001613 T. D. Noe, <a href="/A001613/b001613.txt">Table of n, a(n) for n = 0..1000</a>
%t A001613 Table[FromDigits[DeleteCases[IntegerDigits[n], _?(OddQ[#] &)]], {n, 0, 100}] (* _T. D. Noe_, Aug 09 2012 *)
%K A001613 base,nonn
%O A001613 0,3
%A A001613 _N. J. A. Sloane_