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%I #12 Mar 19 2018 04:18:06
%S 1,1,1,2,2,2,3,3,3,4,5,6,7,7,7,8,8,8,9,10,11,12,12,12,13,13,13,14,15,
%T 16,17,18,19,20,21,22,23,24,25,26,26,26,27,27,27,28,29,30,31,31,31,32,
%U 32,32,33,34,35,36,37,38,39,40,41,42,43,44,45,45,45,46,46,46,47,48,49,50
%N Number of numbers <= n having at least one 0 in their ternary representation.
%C a(n) + A081608(n) = n+1.
%H Robert Israel, <a href="/A081607/b081607.txt">Table of n, a(n) for n = 0..10000</a>
%p f:= n -> `if`(has(convert(n,base,3),0),1,0):
%p ListTools:-PartialSums(map(f, [$0..100])); # _Robert Israel_, Mar 18 2018
%t Accumulate[Boole[Table[DigitCount[n,3,0]>0,{n,0,80}]]] (* _Harvey P. Dale_, Jun 23 2017 *)
%o (PARI) first(n)=my(s,t); vector(n,k, t=Set(digits(k,3)); s+=(t[1]==0)) \\ _Charles R Greathouse IV_, Sep 02 2015
%Y Cf. A007089, A077267, A081609, A081610.
%K nonn
%O 0,4
%A _Reinhard Zumkeller_, Mar 23 2003
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