Exclusive for the Personal Journal of Ekhad and Zeilberger
Written: July 5, 2001
Last update of this page (but not article): May 8, 2012 (thanks to Holger DAMBECK)
I just came from a visit to that Mecca of Classical Combinatorics called Strasbourg, where I had interesting discussions with Dominique Foata and his two disciples, Guo-Niu Han and Bodo Lass. They told me about a charming new result, about the classical (from Feller!) coupon collector problem, that they found, and that surprisingly seems to be new. They found (at least) three insightful proofs, as well as generalizations. Here I offer a 1-page proof of their original result, that I believe to be even shorter than their shortest proof.
Added May 8, 2012: Inspired by Der Spiegel mathematics correspondent Holger DAMBECK's
Email message,
I wrote a
Maple program
that implements the Foata-Han-Lass formula. In particular, to answer his
specific question, the
input file
yields the following
output file.
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