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    李學數說數學故事 / 
    李信明 / 
    九章出版社
 
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    Mathematical Magic Show / Martin Gardner
 
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    mathworld.wolfram.com/MersenneNumber.html
 
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    www.math.swt.edu/~haz/prob_sets/notes/node13.html
 
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    http://mathworld.wolfram.com/OddPerfectNumber.html
 
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    public.logica.com/~stepneys/cyc/p/perfect.htm
 
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    mathworld.wolfram.com/AmicablePair.html
 
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    mathworld.wolfram.com/AbundantNumber.html
 
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    mathworld.wolfram.com/DeficientNumber.html