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 A212283 #15 Apr 28 2019 18:31:40
%S A212283 2,6,4,6,12,21,8,10,20,12,14,172,30,46,16,18,36,20,22,126,46,24,26,
%T A212283 126,28,30,58,60,120,126,32,34,68,36,38,185,78,40,42,126,44,46,90,92,
%U A212283 138,48,50,246,52,54,106,108,56,58,114,60,62,120,182,126,188,378
%N A212283 First a(n) > 1 whose sum of digits is the same in base 2 as in base n.
%C A212283 Theoretically, there might exist an n for which there is no solution, in which case a(n) would be set to 0 by convention; however, no such case was found so far. Problem: does it exist?
%H A212283 Stanislav Sykora, <a href="/A212283/b212283.txt">Table of n, a(n) for n = 2..10000</a>
%e A212283 Example: a(13) = 172 because 172 is the first number >1 such that its expansions in base 2 (10101100) and in base 13 (103) have the same sum of digits, namely 4.
%t A212283 sdn[n_]:=Module[{a=2},While[Total[IntegerDigits[a,2]]!=Total[ IntegerDigits[ a,n]], a++];a]; Array[sdn,70,2] (* _Harvey P. Dale_, May 29 2013 *)
%Y A212283 Cf. A037301, A212222.
%K A212283 nonn,base
%O A212283 2,1
%A A212283 _Stanislav Sykora_, May 08 2012