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 A169884 #17 Aug 22 2025 18:28:16
%S A169884 0,2,4,5,6,8,20,22,24,26,28,40,42,44,46,48,50,55,60,62,64,66,68,80,82,
%T A169884 84,86,88,200,202,204,206,208,220,222,224,226,228,240,242,244,246,248,
%U A169884 260,262,264,266,268,280,282,284,286,288,400,402,404,406
%N A169884 Numbers consisting of either all even digits or just 5's and 0's.
%C A169884 These are all the divisors of zero in carryless arithmetic mod 10. E.g. 5 * 44 = 0.
%H A169884 David Applegate, Marc LeBrun and N. J. A. Sloane, <a href="http://neilsloane.com/doc/carry1.pdf">Carryless Arithmetic (I): The Mod 10 Version</a>.
%H A169884 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%H A169884 <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a>
%t A169884 With[{upto=410},Select[Union[Join[Select[Range[upto],And@@EvenQ[ IntegerDigits[#]]&], FromDigits/@Tuples[{5,0},Ceiling[Log[ 10,upto]]]]],#<=upto&]] (* _Harvey P. Dale_, Aug 05 2011 *)
%t A169884 elect[Range[0,500],AllTrue[IntegerDigits[#],EvenQ]||SubsetQ[{0,5},IntegerDigits[#]]&] (* _Harvey P. Dale_, Aug 22 2025 *)
%Y A169884 Cf. A004520, A059729, A168294, A168541, A169885, A169886, A169887.
%K A169884 nonn,base,easy
%O A169884 1,2
%A A169884 _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Jul 06 2010