$\displaystyle M_{23}=2^{23}-1=8388607$

$\displaystyle \left \lfloor \sqrt{8388607} \right \rfloor=2896$

$\displaystyle 2kp+1=46k+1, \ 1\leq k \leq 62$

Since there are 62 possible values to check, how can this be done in a more efficient fashion?

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- Jul 20th 2010, 01:21 PMdwsmithDetermine whether M_{23} is prime
$\displaystyle M_{23}=2^{23}-1=8388607$

$\displaystyle \left \lfloor \sqrt{8388607} \right \rfloor=2896$

$\displaystyle 2kp+1=46k+1, \ 1\leq k \leq 62$

Since there are 62 possible values to check, how can this be done in a more efficient fashion? - Jul 20th 2010, 01:30 PMundefined
Does this help? Lucas–Lehmer primality test

Edit: The MathWorld page is a bit cleaner than the Wikipedia article at the moment, in my opinion.