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%I #15 Apr 28 2019 18:31:40
%S 2,6,4,6,12,21,8,10,20,12,14,172,30,46,16,18,36,20,22,126,46,24,26,
%T 126,28,30,58,60,120,126,32,34,68,36,38,185,78,40,42,126,44,46,90,92,
%U 138,48,50,246,52,54,106,108,56,58,114,60,62,120,182,126,188,378
%N First a(n) > 1 whose sum of digits is the same in base 2 as in base n.
%C 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 Stanislav Sykora, <a href="/A212283/b212283.txt">Table of n, a(n) for n = 2..10000</a>
%e 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 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 Cf. A037301, A212222.
%K nonn,base
%O 2,1
%A _Stanislav Sykora_, May 08 2012