On the same theme of largish factors, here's one 7 digits above the expected factor size for the B1 (from sequence 230646):

[code][Jul 16 2009, 19:00:32] c74: running 80 ecm curves at B1=5e4...
Using B1=50000, B2=12746592, polynomial x^2, sigma=3055983993
Step 1 took 563ms
Step 2 took 500ms
********** Factor found in step 2: 11308680375499966109748584921767
[Jul 16 2009, 19:00:33] *** prp32 = 11308680375499966109748584921767[/code]

Cofactor was a p43.

Well 232956 is back up to 122 digits. Going to run it a bit higher but the chances of losing the 2^4*31 seem slim.

232960 has a 2^3*3^2*5^2 term at 128 digits. The squares make it possible to escape, but also send it higher very fast. Chance of a single prime is 1/300 so it can happen, but if it isn't soon, the number will go outside the range I can effectively handle.

232800 still doesn't have a driver, but it is up to 129 digits with 2^9 sending it upward.

233100 and 233058 still have the 2^2*7 term at 125 and 127 digits.

Not sure how high I want to take these. There is an interesting conundrum that if you want to break records you need to take them high, but of course it takes much more work on a single sequence that isn't likely to pan out. So if you want large numbers of terminations, you stick with the lower numbers, but if you want records you need to go high. What one really needs is more computers - 4600 dual core for one core per unclaimed sequence would do nicely. :grin:

I am now done with 12270. It just dropped its 3^3 factor completely so someone may be interested in it with only a 2^2 driver. Final status:

12270, i=853, sz 106, C103, +30

363270 1535. [COLOR="Red"]2^9 * 3 * 11 * 31 [/COLOR]c96 sz 105
604560 2347. [COLOR="Red"]2^9 * 3 * 5 * 11 * 31 [/COLOR]c88 sz 105

[SIZE="1"]Cue the 5th Dimension singing "[B]Up, Up and Away[/B]" [/SIZE]

[URL="http://factordb.com/search.php?query=&se=1&aq=379854&action=last&fr=&to="]379854[/URL]: line 915, size 103, 2^5*3
[URL="http://factordb.com/search.php?query=&se=1&aq=386958&action=last&fr=&to="]386958[/URL]: line 995, size 100, 2^6*3
[URL="http://factordb.com/search.php?query=&se=1&aq=392802&action=last&fr=&to="]392802[/URL]: line 1762, size 100, 2^4
[URL="http://factordb.com/search.php?query=&se=1&aq=399942&action=last&fr=&to="]399942[/URL]: line 993, size 100, 2^2*3
[URL="http://factordb.com/search.php?query=&se=1&aq=416040&action=last&fr=&to="]416040[/URL]: line 1466, size 100, 2^2*3*7
[URL="http://factordb.com/search.php?query=&se=1&aq=417600&action=last&fr=&to="]417600[/URL]: line 451, size 100, 2^3*3

I am now done with 11496 and 14160. Statuses:

11496, i=538, sz 107, C101, +20
14160, i=1054, sz 110, C108, +8


14160 is moderately interesting with small factors of only 2*3.

250452 was up to c105 and go slowly down to c60 - but now it`s again going up to c103 :jail:

[quote=gd_barnes;182680] 14160 is moderately interesting with small factors of only 2*3.[/quote]
Actually, 2*3 is a perfect number. It's not moderately interesting, it's quite uninteresting. The perfect numbers are some of the toughest drivers to crack, but don't grow the sequence quickly, making them doubly annoying. I'm pretty sure they get tougher as they get larger, (i.e. 2*3 is easier than 2^2*7, which is easier than 2^4*31, ...) but 2*3 is still quite hard to crack.

[quote=Mini-Geek;182700]Actually, 2*3 is a perfect number. It's not moderately interesting, it's quite uninteresting. The perfect numbers are some of the toughest drivers to crack, but don't grow the sequence quickly, making them doubly annoying. I'm pretty sure they get tougher as they get larger, (i.e. 2*3 is easier than 2^2*7, which is easier than 2^4*31, ...) but 2*3 is still quite hard to crack.[/quote]

Let me just add a note here. Although you can expect to have the 2^12 * 8191 driver for a [I]very[/I] long time, I quote Guy and Selfridge from "What Drives an Aliquot Sequence?",
[quote][FONT=CMR10][SIZE=2][FONT=CMR10][SIZE=2]Despite the tenacity of these drivers, none is expected to live for ever.[/SIZE][/FONT][/SIZE][/FONT][/quote]

556276
 

I usually don't post updates, because the sequences speak for themselves really, but at this moment I couldn't resist.
My pet sequence had another downdriver which it lost and acquired 2*3 which it overnight recently lost to 2^2*3 and just now via 2^2*p[SUB]1mod4[/SUB] acuired the downdriver again -
[URL]http://factordb.com/search.php?query=&se=1&aq=556276&action=last&fr=5950&to=5972[/URL]
Oh, joy, rapture.

[URL="http://factordb.com/search.php?query=&se=1&aq=404460&action=last&fr=&to="]404460[/URL]: line 1731, size 100, 2^2*3^2*7^2
[URL="http://factordb.com/search.php?query=&se=1&aq=426528&action=last&fr=&to="]426528[/URL]: line 1238, size 101, 2^4*3^2*31
[URL="http://factordb.com/search.php?query=&se=1&aq=438768&action=last&fr=&to="]438768[/URL]: line 649, size 102, 2^3*3*5
[URL="http://factordb.com/search.php?query=&se=1&aq=446028&action=last&fr=&to="]446028[/URL]: line 910, size 102, 2^3*3
[URL="http://factordb.com/search.php?query=&se=1&aq=448128&action=last&fr=&to="]448128[/URL]: line 2482, size 100, 2*3^5*5
[URL="http://factordb.com/search.php?query=&se=1&aq=472200&action=last&fr=&to="]472200[/URL]: line 2008, size 100, 2^4*5*7
[URL="http://factordb.com/search.php?query=&se=1&aq=472500&action=last&fr=&to="]472500[/URL]: line 4408, size 100, 2*3^2*5