2016-12-05 22:15:40 +01:00
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Semiprime numbers are natural numbers that are products of exactly two (possibly equal) [[prime_number|prime numbers]].
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2015-02-20 09:02:09 -05:00
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2016-12-05 22:15:40 +01:00
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2017-09-23 10:01:46 +02:00
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'''Semiprimes''' are also known as:
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:::* '''semi-primes'''
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:::* '''biprimes'''
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:::* '''bi-primes'''
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:::* ''' ''2-almost'' ''' primes
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:::* or simply: ''' ''P<sub>2</sub> '' '''
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2016-12-05 22:15:40 +01:00
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;Example:
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<big> 1679 = 23 × 73 </big>
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(This particular number was chosen as the length of the [http://en.wikipedia.org/wiki/Arecibo_message Arecibo message]).
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;Task;
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2015-02-20 09:02:09 -05:00
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Write a function determining whether a given number is semiprime.
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2017-09-23 10:01:46 +02:00
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;See also:
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* The Wikipedia article: [http://mathworld.wolfram.com/Semiprime.html semiprime].
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* The Wikipedia article: [http://mathworld.wolfram.com/AlmostPrime.html almost prime].
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* The OEIS article: [http://oeis.org/A001358 semiprimes] which has a shorter definition: ''the product of two primes''.
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2016-12-05 22:15:40 +01:00
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<br><br>
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