Does anybody know how to prove this series?
∞∑n=1(nlog(2n+12n−1)−1)=1−log22
I arrived at this through Mathematica.
I tried writing log(2n+12n−1) as ∫1012n−12+xdx and −∑∞k=1(−2)kk(2n−1)k but none of them worked.
Answer
Note that
∞∑n=1(nlog(2n+12n−1)−1)=limN→∞N∑n=1(nlog(2n+12n−1)−1)=limN→∞log[e−NN∏n=1(2n+12n−1)n]=limN→∞log[e−N2NN!(2N+1)N(2N)!].
By Stirling's formula, it follows that
e−N2NN!(2N+1)N(2N)!∼√e2.
This immediately yields the desired answer.
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