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From: eklhad@ihnet.UUCP (K. A. Dahlke)
Newsgroups: net.math
Subject: 2n by 2n matrices
Message-ID: <386@ihnet.UUCP>
Date: Wed, 12-Mar-86 17:43:32 EST
Article-I.D.: ihnet.386
Posted: Wed Mar 12 17:43:32 1986
Date-Received: Fri, 14-Mar-86 06:23:56 EST
Distribution: net
Organization: AT&T Bell Laboratories
Lines: 20

Concerning 2n by 2n binary matrices with n ones in each row and column,
Someone (lost the article) wrote a program to count said matrices,
and asked for confirmation.
I thought this was an interesting problem,
and I too wrote a program to count these matrices.
I confirm the results:

  F(1) = 2
  F(2) = 90
  F(3) = 297200
  F(4) = 116963796250

In addition:

  F(5) = 6736218287430460752

-- 
	The moon is more important than the sun, because
	the moon gives us light at night; when we really need it!
			Karl Dahlke    ihnp4!ihnet!eklhad