[QUOTE=jrk;196723][code]Using B1=43000000, B2=388112953420, polynomial Dickson(30), sigma=1033163144
Step 1 took 138254ms
Step 2 took 77893ms
********** Factor found in step 2: 314401460320696602393783174941
Found probable prime factor of 30 digits: 314401460320696602393783174941
Probable prime cofactor 8008382854566027043204017961675695251441834519040939952694150641178698834997735974059700130106717640670945550858659647 has 118 digits
[/code][/QUOTE]

Me too, but with B1=1e6:

[code]Run 55 out of 950:
Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=1225682356
Step 1 took 17734ms
Step 2 took 7328ms
********** Factor found in step 2: 314401460320696602393783174941
Found probable prime factor of 30 digits: 314401460320696602393783174941
Probable prime cofactor 8008382854566027043204017961675695251441834519040939952694150641178698834997735974059700130106717640670945550858659647 has 118 digits
[/code]

[QUOTE=Andi47;196720]...I found this factor by ECM:[code]Found probable prime factor of 43 digits:[/code]
[/QUOTE]Wow! Congrats on that factor! :bow: :bow:

[QUOTE=henryzz;196662]how do you find the optimal polynomial then?
look for the highest alpha or the smallest norms?[/QUOTE]

You can't really except by test sieving, but luckily degree-4 numbers don't take too long.

BTW: 171 digits is a new record height for stability to be achieved. The old record was 164 in 1134 (which also holds the records for highest escapes from 2^5 * 3^2 * 7 and 2^5 * 3).

About 1/3 of t45 done on the c142 so far. In case no factor is found, here is a decent poly:

EDIT: I'm still poly-searching, so a better poly may turn up later.

[code]n: 2348305321333187128721643453051615911877612201981824607595341595725431644675331447201502622476698707484077353247893830745261323782457787822233
# norm 1.016167e-13 alpha -7.694154 e 1.640e-11
skew: 1981323.38
c0: -290064811140012999156642070938904104
c1: 619521716085998538893959511396
c2: -301271769660356610615830
c3: -758842805286610009
c4: -135175380936
c5: 76140
Y0: -1985312530063977010532771629
Y1: 7024691883228631
lpbr: 28
lpba: 28
mfbr: 56
mfba: 56
alambda: 2.6
rlambda: 2.6
alim: 12500000
rlim: 12500000
[/code]

When ECM is finished, sieve with 13e from Q=2M to 20M.

[QUOTE=henryzz;196662]how do you find the optimal polynomial then?
look for the highest alpha or the smallest norms?[/QUOTE]

Why bother? Degree-4 jobs are so fast that you could pick _any_ one of them (found by msieve) and you should be fine.

About 1/2 of t45 is done on the c142.

[QUOTE=jrk;196804]When ECM is finished, sieve with 13e from Q=2M to 20M.[/QUOTE]

Have you tested against 14e?

[QUOTE=10metreh;196855]Have you tested against 14e?[/QUOTE]
Yes

[code]$ for i in `seq 2000000 2000000 20000000`; do ~/ggnfs/bin/gnfs-lasieve4I13e -a test.poly -f $i -c 1000; done
Warning: lowering FB_bound to 1999999.
total yield: 1132, q=2001037 (0.02852 sec/rel)
Warning: lowering FB_bound to 3999999.
total yield: 2029, q=4001003 (0.02795 sec/rel)
Warning: lowering FB_bound to 5999999.
total yield: 1257, q=6001013 (0.02944 sec/rel)
Warning: lowering FB_bound to 7999999.
total yield: 1814, q=8001029 (0.03114 sec/rel)
Warning: lowering FB_bound to 9999999.
total yield: 1255, q=10001009 (0.03446 sec/rel)
Warning: lowering FB_bound to 11999999.
total yield: 1352, q=12001001 (0.03404 sec/rel)
total yield: 1213, q=14001007 (0.03523 sec/rel)
total yield: 1345, q=16001081 (0.03771 sec/rel)
total yield: 1546, q=18001031 (0.03830 sec/rel)
total yield: 1268, q=20001001 (0.04148 sec/rel)[/code]

[code]$ for i in `seq 4000000 2000000 12000000`; do ~/ggnfs/bin/gnfs-lasieve4I14e -a test.poly -f $i -c 1000; done
Warning: lowering FB_bound to 3999999.
total yield: 3986, q=4001003 (0.03817 sec/rel)
Warning: lowering FB_bound to 5999999.
total yield: 2489, q=6001013 (0.03885 sec/rel)
Warning: lowering FB_bound to 7999999.
total yield: 3824, q=8001029 (0.03783 sec/rel)
Warning: lowering FB_bound to 9999999.
total yield: 2675, q=10001009 (0.04045 sec/rel)
Warning: lowering FB_bound to 11999999.
total yield: 2877, q=12001001 (0.03917 sec/rel)[/code]

14e is about 85% as fast as 13e. It would lower the duplication rate, though, so maybe it would be worth the hit. I took a guess that 13e is better.

I stopped poly searching. The best one is still the one posted earlier. I think this number is ready for sieving.

[QUOTE=jrk;196861]
14e is about 85% as fast as 13e. It would lower the duplication rate, though, so maybe it would be worth the hit. I took a guess that 13e is better.[/QUOTE]

So - do we use 13e or 14e?