A Composite number which is the Product of two Primes (possibly equal). They correspond to the 2-Almost Primes. The first few are 4, 6, 9, 10, 14, 15, 21, 22, ... (Sloane's A001358).

**References**

Sloane, N. J. A. Sequence
A001358/M3274
in ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.
*The Encyclopedia of Integer Sequences.* San Diego: Academic Press, 1995.

© 1996-9

1999-05-26