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%I #22 Mar 22 2023 18:32:00
%S 27,54,82,83,84,87,90,99,108,135,163,164,165,168,171,180,189,216,247,
%T 248,250,251,253,254,255,258,262,263,264,267,271,272,273,276,279,288,
%U 298,299,300,303,306,315,325,326,327,330,333,342,351,378,406,407,408,411
%N Numbers having three 0's in base 3.
%H Robert Israel, <a href="/A043323/b043323.txt">Table of n, a(n) for n = 1..10000</a>
%p F:= proc(d,z) option remember;
%p if d = 0 then if z = 0 then return [0] else return [] fi fi;
%p [`if`(z>0, op(procname(d-1,z-1)),NULL),
%p op(map(`+`,procname(d-1,z),3^(d-1))),
%p op(map(`+`,procname(d-1,z),2*3^(d-1)))]
%p end proc:
%p f:= proc(d)
%p op(map(`+`,F(d-1,3),3^(d-1))),
%p op(map(`+`,F(d-1,3),2*3^(d-1)))
%p end proc:
%p seq(f(d),d=4..6); # _Robert Israel_, Mar 22 2023
%t Select[Range[400],DigitCount[#,3,0]==3&] (* _Harvey P. Dale_, Jan 18 2015 *)
%Y Cf. A007089.
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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