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%I #19 Oct 20 2016 12:55:07
%S 0,0,0,0,0,0,0,1,1,1,1,2,2,3,4,5,5,5,5,6,6,7,8,9,9,10,11,12,13,14,15,
%T 16,16,16,16,17,17,18,19,20,20,21,22,23,24,25,26,27,27,28,29,30,31,32,
%U 33,34,35,36,37,38,39,40,41,41,41,41,41,42
%N a(n) = Sum_{i=1..n} (floor(S2(i)/3) mod 2), where S2(i) = A000120(i).
%C Sequence A115384 is a(n) = Sum_{i=1..n} (floor(S2(n)*1/1) mod 2) = Sum_{i=1..n} (S2(n) mod 2).
%H G. C. Greubel, <a href="/A135585/b135585.txt">Table of n, a(n) for n = 0..1000</a>
%p A000120 := proc(n) local i ; add(i,i=convert(n,base,2)) : end: A135585 := proc(n) add(floor(A000120(i)/3) mod 2,i=1..n) ; end: seq(A135585(n),n=0..80) ; # _R. J. Mathar_, Apr 22 2008
%t f[n_] := n - Sum[Floor[n/2^k], {k, 1, Infinity}]; Table[Sum[Mod[Floor[f[i]/3], 2], {i,1,n}], {n,0,25}] (* _G. C. Greubel_, Oct 20 2016 *)
%o (PARI) a(n) = sum(i=1, n, hammingweight(i)\3 % 2); \\ _Michel Marcus_, Sep 19 2015
%Y Cf. A115384, A010060.
%K easy,nonn,base
%O 0,12
%A _Ctibor O. Zizka_, Feb 25 2008
%E Definition corrected by _R. J. Mathar_, Apr 22 2008
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