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Let a Divisor  of
 of  be called a 1-ary divisor if
 be called a 1-ary divisor if  . Then
. Then  is called a
 is called a  -ary divisor of
-ary divisor of  ,
written
,
written  , if the Greatest Common
, if the Greatest Common  -ary divisor of
-ary divisor of  and
 and  is 1.
 is 1.
In this notation,  is written
 is written  , and
, and  is written
 is written  .
.   is an Infinary Divisor
of
 is an Infinary Divisor
of  (with
 (with  ) if
) if  .
.
See also Divisor, Greatest Common Divisor, Infinary Divisor
References
Guy, R. K.  Unsolved Problems in Number Theory, 2nd ed.  New York: Springer-Verlag, p. 54, 1994.