Reserved for MF - Sequence 4788

[Andi47]

Originally Posted by 10metreh

A C161.

This seems to be near the crossover between the 14e and 15e sievers....

[Andi47]

GMP-ECM 6.2.3 [powered by GMP 4.3.0] [ECM]
Input number is 41989040709803320172325437685122012188238989866495646783169593798391300698922442158422655234035792573779700795308983586334745780088868313272292796749799498704069 (161 digits)

...

Run 3 out of 2000:
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=2746202462
Step 1 took 855859ms
Step 2 took 182687ms
********** Factor found in step 2: 17929080031745140528449157941308074577509
Found probable prime factor of 41 digits: 17929080031745140528449157941308074577509
Probable prime cofactor 2341951769720349963952569043284852276019038780750832785187060203064697177590116136874365861798306068919218595003497391841 has 121 digits

[fivemack]

I had completed 700@1e8 without finding that, which is actually quite unlucky (ecm -v says 644 curves at 1e8 for a p45)

Killed them and started again on the C145 from 2459.

[Greebley]

Boy that factor of 3 just won't go away. I guess at this many digits the chance of at least one factor + 1 being divisible by 3 is high.

[mdettweiler]

Originally Posted by Greebley

Boy that factor of 3 just won't go away. I guess at this many digits the chance of at least one factor + 1 being divisible by 3 is high.

Hmm...if I understand this correctly, then it's going to lose the 3 on the next line! Here's the current partial factorization of line 2459:

1389005994...<168> = 24 · 3 · 11 · 593 · 811 · 81266036243201<14> · 6731092709...<145>

Notice the 11: 11+1=12, which is divisible by 3.

[fivemack]

(mdettweiler: you need to have *none* of the factors 2 mod 3 to lose the 3)

(job 5 out of 16) Run 12 out of 125:
Using B1=100000000, B2=776268975310, polynomial Dickson(30), sigma=1209849063
Step 1 took 1004841ms
Step 2 took 277472ms
********** Factor found in step 2: 1235256026055614152023140734345351300023869925971
Found probable prime factor of 49 digits: 1235256026055614152023140734345351300023869925971
Probable prime cofactor 5449147842682529938683571528241234609478304810765641311200653978116824057163714349422254281192109 has 97 digits

Next line has C145, will give it the same treatment

Edit: found a P30 (ten times) and P37 (once) in 16x125 @ 1e6

[axn]

Originally Posted by mdettweiler

Hmm...if I understand this correctly, then it's going to lose the 3 on the next line! Here's the current partial factorization of line 2459:
<snip>
Notice the 11: 11+1=12, which is divisible by 3.

Which is why it can NOT lose the 3 on that iteration

[bsquared]

I see we've now hit 170 digits... what is the record and if not this one, what is the highest sequence?

[mdettweiler]

Originally Posted by fivemack

(mdettweiler: you need to have *none* of the factors 2 mod 3 to lose the 3)

Originally Posted by axn

Which is why it can NOT lose the 3 on that iteration

Ah, I see. Thanks for the explanation.

[10metreh]

Originally Posted by bsquared

I see we've now hit 170 digits... what is the record and if not this one, what is the highest sequence?

162126 (171 digits)

[henryzz]

Originally Posted by 10metreh

162126 (171 digits)

looking at the database it looks like it is actually 173 digits
looking at the karsten's records page it looks like 175 digits