ecn-ec:ecn-pc:ecn-ed:vu@pur-ee.UUCP (08/30/83)
I read this problem sometime last year. Probably it was some old problem from some old contest (W. L. Putnam Comp, or USSR olympiad, or the International Math Olympiad). A secretary wrote n letters and addressed n envelopes. Calculate the probability that she got p ( 0 <= p <= n ) letters in the right envelopes if she stuffed them randomly. Please mail answers, comments, flames, references, anything, ... to pur-ee!norris since my current account pur-ee!vu will be terminated soon. In the meantime, I will make another raid in the library to find the original problem. Hao-Nhien Vu. Purdue U.