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 A135121 #14 Sep 04 2014 11:22:39
%S A135121 0,1,6,7,10,11,60,61,180,181,285,300,301,575,687,754,826,827,882,883,
%T A135121 900,901,910,911,1254,1305,1311,1326,1327,1335,1377,1383,1386,1387,
%U A135121 1395,1431,1506,1507,1532,1626,1627,1650,1651,1890,1891,1955,2013,2036,2040
%N A135121 Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 5 all are equal.
%H A135121 Stanislav Sykora, <a href="/A135121/b135121.txt">Table of n, a(n) for n = 1..10000</a>
%e A135121 a(2)=6, since ds_2(6)=ds_3(6)=ds_5(6), where ds_x=digital sum base x.
%t A135121 Select[Range[0,3000],Length[Union[Total/@IntegerDigits[#,{2,3,5}]]]==1&] (* _Harvey P. Dale_, Sep 04 2014 *)
%Y A135121 Cf. A007953, A054899, A131451, A133620, A133900, A134599, A135100, A135110, A135120, A037308, A212222.
%K A135121 nonn,base
%O A135121 1,3
%A A135121 _Hieronymus Fischer_, Dec 31 2007
%E A135121 Added 0, _Stanislav Sykora_, May 06 2012