PrimeNet has composite factors recorded
 

I thought that PrimeNet checks reported factors for primality, and only recorded the prime factors. I've found that this isn't entirely true ([url=http://v5www.mersenne.org/report_exponent/?exp_lo=33835283]for example[/url]). Perhaps these exponents were checked and reported before that composite-factor checking code was put into place, but it seems it was never run retroactively on existing PrimeNet data. Here's the list of exponents with composite factors I've found so far (checking 10M<x<50M). Would it be useful if I reported other ones I came across?

[code]
`exponent` = "33727879" AND `factor` = "5241921746317679593";
`exponent` = "33743551" AND `factor` = "2172500766827159033";
`exponent` = "33778631" AND `factor` = "164303413861337879";
`exponent` = "33778631" AND `factor` = "766749264438533471";
`exponent` = "33780781" AND `factor` = "328648657335510943";
`exponent` = "33818431" AND `factor` = "50066010406277663449";
`exponent` = "33818699" AND `factor` = "260764607590962113";
`exponent` = "33818699" AND `factor` = "347686143432070351";
`exponent` = "33821783" AND `factor` = "2036165179601408857";
`exponent` = "33821783" AND `factor` = "6703330310218129297";
`exponent` = "33828491" AND `factor` = "1043662540136866751";
`exponent` = "33828497" AND `factor` = "54929626518991391";
`exponent` = "33830651" AND `factor` = "6922014315938878903";
`exponent` = "33831823" AND `factor` = "24448490479274199599";
`exponent` = "33831823" AND `factor` = "2586778487341833769";
`exponent` = "33831823" AND `factor` = "274702140551080943";
`exponent` = "33831823" AND `factor` = "58676377049087395537";
`exponent` = "33831823" AND `factor` = "6208268358916012247";
`exponent` = "33833461" AND `factor` = "315938052733171769";
`exponent` = "33835019" AND `factor` = "3461900942741925199";
`exponent` = "33835019" AND `factor` = "4615867921761139201";
`exponent` = "33835019" AND `factor` = "494557278056586751";
`exponent` = "33835271" AND `factor` = "13687534446364740217";
`exponent` = "33835283" AND `factor` = "1868356672803486743";
`exponent` = "33835471" AND `factor` = "4945704917416031303";
`exponent` = "33835589" AND `factor` = "10789038919651481959";
[/code]

Fixed. Email me if you find more composites

I've just spent the past 10 days checking ~33.5 million factors (what PrimeNet knew about at the beginning of July 2011), and no further composite factors were found.

I'm now running through checking for new factors since my last database update, and I found one already:

[url=http://v5www.mersenne.org/report_exponent/?exp_lo=99079]M99079[/url] - [i]99079,1412184542980087,2010-08-03 21:11[/i]
1412184542980087 = 1783423 * 791839369 (both are already listed)

Another small batch found around 9M:

9000379,7558908623076911641,2010-09-23 20:42
=> 216009097
=> 34993473553

9000683,152951220467377351,2010-09-23 19:47
=> 18001367
=> 8496644753

9000637,1356131972798354113,2010-09-23 20:16
=> 54003823
=> 25111777231

9028337,3912521837704031,2010-10-10 08:35
=> 54170023
=> 72226697