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| | [No title] (Site not responding. Last check: 2007-11-07) |
 | | (I believe that the question of whether odd perfect numbers exist is the oldest open question in mathematics, now about 2 and a half millenia old!) It is known that an even number is perfect iff it is of the form 2^(p-1) * ((2^p) - 1) where the second factor is prime. |
 | | As is well known, an odd perfect number $N$, if one exists, must be of the form $N=p\sp \alpha q\sp {2\beta\sb 1}\sb 1 q\sp {2\beta\sb 2}\sb 2\cdots q\sp {2\beta\sb \tau}\sb t$ for distinct odd primes $p,q\sb 1,q\sb 2,\cdots,q\sb t$, with $p\equiv\alpha\equiv1\bmod4$. |
 | | They also show that if $x$ is the number of prime powers $q\sp {2\beta\sb i}\sb i$ for which both $q\sb i\equiv1\bmod 4$ and $\beta\sb i\equiv1\bmod2$, then $p-\alpha\equiv4x\bmod8$. |
| www.math.niu.edu /~rusin/known-math/98/perfect (596 words) |
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