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%I #17 Jun 29 2021 02:19:10
%S 7,51,52,53,54,55,63,70,77,84,91,99,105,148,154,197,203,246,252,295,
%T 301,344,350,359,360,361,362,363,366,367,368,369,370,373,374,375,376,
%U 377,380,381,382,383,384,387,388,389,390,391,392,443,444,445,446,447
%N Numbers whose base-7 representation has the same nonzero number of 0's and 1's.
%H Robert Israel, <a href="/A039308/b039308.txt">Table of n, a(n) for n = 1..10000</a>
%p filter:= proc(n) local L,t;
%p L:= convert(n,base,7);
%p t:= numboccur(0,L);
%p t=numboccur(1,L) and t>0
%p end proc:
%p select(filter, [$1..447]); # _Robert Israel_, Jul 18 2018
%t Select[Range[500],DigitCount[#,7,0]==DigitCount[#,7,1]>0&] (* _Harvey P. Dale_, Jun 21 2019 *)
%Y Cf. A007093.
%K nonn,base,easy
%O 1,1
%A _Olivier Gérard_
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