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A161560 a(n) = floor(A000069(n)/2-1/2). 1

%I

%S 0,0,1,3,3,5,6,6,7,9,10,10,12,12,13,15,15,17,18,18,20,20,21,23,24,24,

%T 25,27,27,29,30,30,31,33,34,34,36,36,37,39,40,40,41,43,43,45,46,46,48,

%U 48,49,51,51,53,54,54,55,57,58,58,60,60,61,63,63,65,66,66,68,68,69,71,72

%N a(n) = floor(A000069(n)/2-1/2).

%C Plays the role of an inverse function to A093505.

%F a(n) = A000069(n) - n.

%e a(5) = 3 because the fifth odious number = 8 and floor(8/2 - 1/2) = 3. Also 8 - 5 = 3.

%o (PARI) a(n)=n-1-hammingweight(n-1)%2 \\ _Charles R Greathouse IV_, Mar 29 2013

%Y Cf. A000069.

%K nonn,easy

%O 1,4

%A _Jaroslav Krizek_, Jun 13 2009

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Last modified January 23 14:34 EST 2022. Contains 350512 sequences. (Running on oeis4.)