Hudalrichus Regius

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Hudalrichus Regius

fl. 1530s

Mathematician who showed that not all numbers of the form 2n-1 for all primes n are themselves prime. Up to Regius's time, mathematicians had assumed that this was so, since 22-1=3, 23-1=7, 25-1=31, and so on. However, Regius showed that the result of 211-1 is not a prime number: its result, 2047, is equal to 23 multiplied by 89.

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Hudalrichus Regius

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