Brown numbers are Pairs of Integers satisfying the condition of Brocard's
Problem, i.e., such that

where is the Factorial and is a Square Number. Only three such Pairs of numbers are known: (5,4), (11,5), (71,7), and Erdös conjectured that these are the only three such Pairs.

**References**

Guy, R. K. *Unsolved Problems in Number Theory, 2nd ed.* New York: Springer-Verlag, p. 193, 1994.

Pickover, C. A. *Keys to Infinity.* New York: Wiley, p. 170, 1995.

© 1996-9

1999-05-26