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Is there a closed formula to the problem $f(1)=1, f(2n)=f(n), f(2n+1)=f(2n)+1$. So far i have found a solution for $n$, which is the number of power of $2$'s needed to add up to the number starting with the greatest power of $2$. Also $n=$ the number of $1$'s needed to represent $n$ in binary form. So for example $f(12)=2, 2^3 + 2^2 = 12$, $12$ in binary is represented as $1100$, two $1$'s so $n=2$. My problem is i know the process but can't find a simple formula to this problem.

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    Are you sure that there is a simpler method than counting the number of $1$s in the binary expansion?2011-12-03
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    A related function is ["fusc", a name coined by Dijkstra](http://www.cs.utexas.edu/~EWD/transcriptions/EWD05xx/EWD578.html). See also [here](http://www.cut-the-knot.org/blue/FuscProperty.shtml).2011-12-03

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