If p, q are integers so that q>p>1, show that 1/p+ 1/(p+1)+ 1/(p+2)+ ... +1/q cannot be an integer.

(In reply to Solution by David Shin)

Oops, a bit careless with my last inequality.  To correct my proof, note that there is an even number between x and y; i.e., some z such that x < 2z < y.  The inequality to use then is:

p <= x*2^k < z*2^{k+1) < y*2^k <= q,

Posted by David Shin on 2004-10-06 16:34:28