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-   -   bugged sequence in factordb (https://www.mersenneforum.org/showthread.php?t=13528)

firejuggler 2010-06-14 18:51

bugged sequence in factordb
 
while browsing aliquot sequence, I stumbled upon these
[code]
Start [URL="http://factorization.ath.cx/search.php?so=1&se=1&1=1&start=2&limit=100&len=1"]Length[/URL] End [URL="http://factorization.ath.cx/search.php?so=1&se=1&1=1&start=2&limit=100&ew=1"]Ends with[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=794280&action=last20"]794280[/URL] 830 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99428980"]P107[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=794196&action=last20"]794196[/URL] 438 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99111241"]P106[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=789090&action=last20"]789090[/URL] 597 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99137099"]P101[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=789740&action=last20"]789740[/URL] 608 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=97848678"]P100[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=790248&action=last20"]790248[/URL] 1278 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=98857033"]P91[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=792756&action=last20"]792756[/URL] 703 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99116241"]P90[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=790884&action=last20"]790884[/URL] 1193 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99116242"]P89[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=794880&action=last20"]794880[/URL] 560 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99429079"]P85[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=792864&action=last20"]792864[/URL] 887 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99116494"]P85[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=792820&action=last20"]792820[/URL] 835 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99110422"]P85[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=791196&action=last20"]791196[/URL] 1853 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=83083183"]P83[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=789816&action=last20"]789816[/URL] 1030 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=99429246"]P82[/URL]
[URL="http://factorization.ath.cx/search.php?se=1&aq=765552&action=last20"]765552[/URL] 103 [COLOR=#00cc00]Prime[/COLOR] [URL="http://factorization.ath.cx/search.php?id=61344466"]P27[/URL]
[/code]
all these end in a 'even' prime... wich is just wrong. I tried to repair the sequence many time without success

10metreh 2010-06-15 10:39

This bug is known. There used to be a "Set prime" button which was given to certain (trusted) users of the DB. It was meant to be used on very large numbers that had been proved prime. However, it obviously got given to someone with malicious intents by mistake, and that person used it to set various composite numbers prime. The "Set prime" button was removed.

Andi47 2010-06-15 14:03

I thought the false primes have been fixed when the "set prime" button was removed. (AFIK Syd has (or intended to?) set all primes to "unknown" followed by a primality check.)

I have emailed Syd about the (new?) false primes yesterday in the late evening (Central European Summer Time).


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