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- Apr 16th 2008, 12:37 AMmilfnerFermat pseudoprime
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- May 2nd 2008, 08:45 PMjtsab
For the 1st one, its easy to see that $\displaystyle 91 = 7 * 13$ so its definitely not prime.

Also $\displaystyle 3^{90} = 1mod\ 90$ (from observation)

You can also construct a new pseudoprime N using the proposition:

*Let b >= 2 (where b is the base of this pseudoprime) and p an odd prime where p does not divide b(b-1)(b+1) then*$\displaystyle N = \frac{b^p -1}{b-1}*\frac{b^p+1}{b+1}$

If someone could review this and check for correctness, that would be great! :)

**Edit:**it works fine. - May 2nd 2008, 09:15 PMmilfner
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