释义 |
Least Common MultipleThe least common multiple of two numbers and is denoted or and can be obtainedby finding the Prime factorization of each
 | (1) |
 | (2) |
where the s are all Prime Factors of and , and if does not occur in one factorization, then the corresponding exponent is 0. The least common multiple is then
 | (3) |
Let be a common multiple of and so that
 | (4) |
Write and , where and are Relatively Prime by definition of the GreatestCommon Divisor . Then , and from the Division Lemma (given that isDivisible by and ), we have is Divisible by , so
 | (5) |
 | (6) |
The smallest is given by ,
 | (7) |
so
 | (8) |
 | (9) |
The LCM is Idempotent
 | (10) |
Commutative
 | (11) |
Associative
 | (12) |
Distributive
 | (13) |
and satisfies the Absorption Law
 | (14) |
It is also true that
 | (15) |
See also Greatest Common Divisor, Mangoldt Function, Relatively Prime References
Guy, R. K. ``Density of a Sequence with L.C.M. of Each Pair Less than .'' §E2 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 200-201, 1994.
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