Factoring database - Page 38

10metreh · 2009-06-18, 06:12

Quote:

Originally Posted by Syd

I did some optimizations on the database that locked up queries for some time. This night I'll do some more, maybe it goes offline again.

Btw, what about a shorter domain?

http://factordb.com/

I was wondering, where on earth did the ".ath.cx" come from?

Uncwilly · 2009-06-18, 06:18

Quote:

Originally Posted by 10metreh

I was wondering, where on earth did the ".ath.cx" come from?

It was a christmas present:
http://en.wikipedia.org/wiki/.cx

10metreh · 2009-06-18, 06:21

Quote:

Originally Posted by Uncwilly

It was a christmas present:
http://en.wikipedia.org/wiki/.cx

I knew about the .cx, what about the .ath?

Andi47 · 2009-06-20, 16:25

The "squared line" bug strikes again: http://www.mersenneforum.org/showthread.php?t=12064

Andi47 · 2009-06-20, 20:46

Quote:

Originally Posted by Andi47

The "squared line" bug strikes again: http://www.mersenneforum.org/showthread.php?t=12064

Another issue (bug?), mentioned in the same thread:

Quote:

Originally Posted by Greebley

This seems to be my day for finding database issues:
for sequence 125970 entry 107 is wrong - it has a different number than it should. This is what it should be:

106 . 79289831227886721316 = 2^2 * 7 * 19 * 10337827 * 14417056519
107 . 87636145410556465884 = 2^2 * 3 * 7 * 79 * 269 * 49093569496201

Note that you can tell the other value is wrong because it ends 64, but the sigma has 19+1 factor and 144..519+1 factor and so ends 00, but
...00 - ...16 means the next one should end ...84.

I tried sending the correct sequence to the DB, but it didn't update to the correct value. Also what does the CF mean? (instead of ff)

Do I need to post in the other thread mentioned to get this fixed?

R. Gerbicz · 2009-06-21, 00:24

CF=composite factor

10metreh · 2009-06-21, 06:27

Quote:

Originally Posted by R. Gerbicz

CF=composite factor

It's "composite with known factors"

Mini-Geek · 2009-06-22, 15:09

I'd like to suggest these sequences be added as new sequence types: (the sequence number could be the starting value)
http://www.research.att.com/~njas/sequences/A000945 "Euclid-Mullin sequence: a(1) = 2, a(n+1) is smallest prime factor of Product_{k=1..n} a(k) + 1." some work/discussion at mersenneforum here: http://www.mersenneforum.org/showthread.php?t=3619
http://www.research.att.com/~njas/sequences/A000946 "Euclid-Mullin sequence: a(1) = 2, a(n+1) is largest prime factor of Product_{k=1..n} a(k) + 1."
And this:
http://www.research.att.com/~njas/sequences/A000058 "Sylvester's sequence: a(n+1) = a(n)^2 - a(n) + 1, with a(0) = 2." a.k.a. Euclid sequence, (I prefer this name because the sequence is related to Euclid's proof of infinite primes) the formula there makes it look more complicated than it is IMO, it's like the above sequences but with all prime factors multiplied on; some old discussion here: http://www.mersenneforum.org/showthread.php?t=953
Regarding whether the Euclid sequence should be a sequence (like Aliquot, home prime, etc.) or a number type (not sure what you call it, but e.g. Mersennes, factorials, Lucas numbers, etc.): you don't need to know the factorization of the previous line in order to know the next one, which would place it in number type and not sequence, but being able to change starting values would be good, which would place it in sequences. I'm not really sure which would be better, but if it's not too hard, I think it'd be good to have it as a two-variable number type, e.g. E(2,10) is the 10th term of the Euclid sequence beginning with 2.

As far as I can tell, no real effort has been put towards any of these sequences in years (except some year-old P-1 and ECM work towards the c180 blocking A000945). Maybe this will help their visibility and get some people to try to factor them!

Andi47 · 2009-06-22, 15:41

Quote:

Originally Posted by Andi47

The "squared line" bug strikes again: http://www.mersenneforum.org/showthread.php?t=12064

Several sequences which have been scrambled due to various bugs have accumulated by now, see the thread mentioned above.

Andi47 · 2009-06-27, 07:04

Some more scrambled sequences have been reported to the thread in the "Aliquot sequences" subforum, and some of the old errors are still present.

Does the database check the integrity of factors when a file of them is reported?

@Syd: Suggestion (also posted in the thread over there): Please introduce a button to check the integrity of sequences - which corects the error and sends a mail to you if an error is found.

10metreh · 2009-06-27, 07:07

Something I've been thinking of for a while is whether the database should be given a subforum inside "Factoring". This thread is now very long, and it is hard to find what you want. Also, there are various separate problems that should have their own threads, and there is no subforum specially for these threads (yet). What do you think?

2009-06-22, 15:09	#415
Mini-Geek Account Deleted "Tim Sorbera" Aug 2006 San Antonio, TX USA 10253₈ Posts	I'd like to suggest these sequences be added as new sequence types: (the sequence number could be the starting value) http://www.research.att.com/~njas/sequences/A000945 "Euclid-Mullin sequence: a(1) = 2, a(n+1) is smallest prime factor of Product_{k=1..n} a(k) + 1." some work/discussion at mersenneforum here: http://www.mersenneforum.org/showthread.php?t=3619 http://www.research.att.com/~njas/sequences/A000946 "Euclid-Mullin sequence: a(1) = 2, a(n+1) is largest prime factor of Product_{k=1..n} a(k) + 1." And this: http://www.research.att.com/~njas/sequences/A000058 "Sylvester's sequence: a(n+1) = a(n)^2 - a(n) + 1, with a(0) = 2." a.k.a. Euclid sequence, (I prefer this name because the sequence is related to Euclid's proof of infinite primes) the formula there makes it look more complicated than it is IMO, it's like the above sequences but with all prime factors multiplied on; some old discussion here: http://www.mersenneforum.org/showthread.php?t=953 Regarding whether the Euclid sequence should be a sequence (like Aliquot, home prime, etc.) or a number type (not sure what you call it, but e.g. Mersennes, factorials, Lucas numbers, etc.): you don't need to know the factorization of the previous line in order to know the next one, which would place it in number type and not sequence, but being able to change starting values would be good, which would place it in sequences. I'm not really sure which would be better, but if it's not too hard, I think it'd be good to have it as a two-variable number type, e.g. E(2,10) is the 10th term of the Euclid sequence beginning with 2. As far as I can tell, no real effort has been put towards any of these sequences in years (except some year-old P-1 and ECM work towards the c180 blocking A000945). Maybe this will help their visibility and get some people to try to factor them! Last fiddled with by Mini-Geek on 2009-06-22 at 15:21

2009-06-27, 07:04	#417
Andi47 Oct 2004 Austria 2×17×73 Posts	Some more scrambled sequences have been reported to the thread in the "Aliquot sequences" subforum, and some of the old errors are still present. Does the database check the integrity of factors when a file of them is reported? @Syd: Suggestion (also posted in the thread over there): Please introduce a button to check the integrity of sequences - which corects the error and sends a mail to you if an error is found. Last fiddled with by Andi47 on 2009-06-27 at 07:05

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2009-06-20, 16:25	#411
Andi47 Oct 2004 Austria 9B2₁₆ Posts	The "squared line" bug strikes again: http://www.mersenneforum.org/showthread.php?t=12064

2009-06-21, 00:24	#413
R. Gerbicz "Robert Gerbicz" Oct 2005 Hungary 2·743 Posts	CF=composite factor

2009-06-27, 07:07	#418
10metreh Nov 2008 2322₁₀ Posts	Something I've been thinking of for a while is whether the database should be given a subforum inside "Factoring". This thread is now very long, and it is hard to find what you want. Also, there are various separate problems that should have their own threads, and there is no subforum specially for these threads (yet). What do you think?