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Numbers whose base-12 representation has the same number of 1's and 4's.
1

%I #17 Jun 26 2021 15:48:22

%S 0,2,3,5,6,7,8,9,10,11,16,24,26,27,29,30,31,32,33,34,35,36,38,39,41,

%T 42,43,44,45,46,47,49,60,62,63,65,66,67,68,69,70,71,72,74,75,77,78,79,

%U 80,81,82,83,84,86,87,89,90,91,92,93,94,95,96,98,99,101,102,103,104

%N Numbers whose base-12 representation has the same number of 1's and 4's.

%H Robert Israel, <a href="/A039222/b039222.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= proc(n) local F;

%p F:= convert(n,base,12);

%p numboccur(1,F)=numboccur(4,F)

%p end proc:

%p select(filter, [$0..200]); # _Robert Israel_, Apr 15 2019

%t Select[Range[0,120],DigitCount[#,12,1]==DigitCount[#,12,4]&] (* _Harvey P. Dale_, Mar 12 2018 *)

%o (PARI) isok(n) = my(d=digits(n, 12)); #select(x->(x==1), d) == #select(x->(x==4), d); \\ _Michel Marcus_, Apr 16 2019

%K nonn,base,easy

%O 1,2

%A _Olivier GĂ©rard_