5th Putnam 1942

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Problem A3

Does ∑n≥0 n! kn/(n + 1)n converge or diverge for k = 19/7?

 

Solution

The nth term divided by the n-1th term is k n nn-1/(n+1)n = k/(1 + 1/n)n which tends to k/e. But k/e < 1, so the series converges by the ratio test.

 


 

5th Putnam 1942

© John Scholes
jscholes@kalva.demon.co.uk
5 Mar 2002