limn→∞(1+1n)n converges since:
(1) From the binomial theorem:
(1+1n)n=n∑k=0(nk)(1n)k= =1+n!(n−1)!(1n)+n!(n−2)!2!(1n)2+n!(n−3)!3!(1n)3+⋯+n!n!(1n)n
=1+1+n−12!(1n)+(n−1)(n−2)3!(1n)2+⋯+(n−1)(n−2)…(2)n!(1n)n−1
=1+1+12!(1−1n)+13!(1−1n)(1−2n)+⋯+ +1n!(1−1n)(1−2n)…(1−n−1n)≤10!+11!+12!+13!+⋯+1n!
(2) From this result, we know that limn→∞n∑i=0(1i!) converges.
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