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From: pumphrey@ttidcb.UUCP (Larry Pumphrey)
Newsgroups: net.math,net.physics,net.puzzle
Subject: Re:Re: summation in closed form
Message-ID: <561@ttidcb.UUCP>
Date: Tue, 3-Dec-85 09:13:12 EST
Article-I.D.: ttidcb.561
Posted: Tue Dec  3 09:13:12 1985
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Organization: TTI, Santa Monica, CA.
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Xref: watmath net.math:2594 net.physics:3657 net.puzzle:1222


>> For k>=0, let a(k) be  2^k / k  (one over k, times the kth power of 2).
>> Can you find the sum of a(k) as k ranges from 1 to n as a closed formula
>> in n?

>> I suspect not, but cannot yet find a way to show that it is impossible.

>  I suspect so,  how about

>                k=n    2^k          (n+2)
>        f(n) = sigma  -----  =  2 - -----
>                k=0     k            2^n

   I'll print my own correction, my erroneous "solution" was broadcast
   before I had a chance to retract it.  Obviously, I interchanged the
   numerator and denominator which makes the problem trivial.  Sorry
   about that  :-(