could anyone help me figure out whether this infinite series
∞∑n=1(1−ln(n)n)2n
diverges?
I've tried using Cauchy's and d'Alembert's limit tests but both gave the result 1. I've also tried the necessary condition for convergence, but
limn→∞(1−ln(n)n)2n=0
Answer
Use
∞∑n=1(1−lognn)2n≤∞∑n=1(exp(−lognn))2n=∞∑n=1exp(−2logn)=∞∑n=11n2<∞.
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