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A043423 Numbers having three 0's in base 8.

%I A043423 #14 Apr 24 2021 17:40:13
%S A043423 512,1024,1536,2048,2560,3072,3584,4097,4098,4099,4100,4101,4102,4103,
%T A043423 4104,4112,4120,4128,4136,4144,4152,4160,4224,4288,4352,4416,4480,
%U A043423 4544,4608,5120,5632,6144,6656,7168,7680,8193,8194
%N A043423 Numbers having three 0's in base 8.
%H A043423 Robert Israel, <a href="/A043423/b043423.txt">Table of n, a(n) for n = 1..10000</a>
%p A043423 g:= proc(x) local j; seq(8*x+j,j=1..7) end proc:
%p A043423 h:= x -> 8*x:
%p A043423 B[1,0]:= {$1..7}:
%p A043423 for d from 2 to 5 do
%p A043423   B[d,0]:= map(g, B[d-1,0]);
%p A043423   for i from 1 to min(d-2,3) do
%p A043423     B[d,i]:= map(g, B[d-1,i]) union map(h, B[d-1,i-1])
%p A043423   od;
%p A043423   if d <= 4 then B[d,d-1]:= map(h, B[d-1,d-2]) fi;
%p A043423 od:
%p A043423 sort(convert(B[4,3] union B[5,3], list)); # _Robert Israel_, Jan 15 2019
%t A043423 Select[Range[10000],DigitCount[#,8,0]==3&] (* _Harvey P. Dale_, Nov 25 2018 *)
%Y A043423 Cf. A007094.
%K A043423 nonn,base
%O A043423 1,1
%A A043423 _Clark Kimberling_