A039073 - OEIS

%I #13 Jun 20 2021 15:46:38

%S 0,1,2,3,5,6,8,9,10,11,13,14,16,17,18,19,21,22,24,25,26,27,29,30,39,

%T 40,41,42,43,45,46,48,49,50,51,53,54,60,64,65,66,67,69,70,72,73,74,75,

%U 77,78,80,81,82,83,85,86,88,89,90,91,93,94,103,104,105,106,107,109

%N Numbers whose base-8 representation has the same number of 4's and 7's.

%t b847Q[n_]:=Module[{dcn=DigitCount[n,8]},dcn[[4]]==dcn[[7]]]; Select[ Range[ 0, 150], b847Q] (* _Harvey P. Dale_, Oct 20 2011 *)

%K nonn,base,easy

%O 1,3

%A _Olivier Gérard_