Riesel Primes k*2^n-1, k<300 [Was "k=1"]

[Kosmaj]

I completed k=57, 61, 83, 85, and 87 to 400k. I found the following primes:
61*2^384287-1
87*2^353734-1
87*2^360829-1
87*2^382268-1

I'm continuing work on k=67, 85, and 87.
I'd like to reserve k=79 from 300k and k=71 from 417k.
I'm also working on k=7, 21, 55, and 77.

I'm releasing, for the time being, k=57, 61 and 83.

[Harvey563]

I checked k=219, 221, 223, & 227 from 200000 to 210000 with no primes found.
k=243 is checked to 230000 with no new primes.

Harvey563

[cyrix]

Hi,

I'd like to work on k=105 a little bit further.

Cyrix

[JCS]

Hi Cyrix,

I am nearly done checking 105 up to 500,000. With only 1600 n's remaining, there have been no new primes since n=280022. Fairness would dictate that I'm long overdue for another prime, but then we know that large primes are anything but fair. You're welcome to join me for the last few laps.

I have also completed k=255 from 260,000 to 320,000. There was only one new prime, for n=281366.

For a dense, low k candidate, you may want to look at k=69. It has 68 primes for n less than 200k, and 7 primes between 200k and 500k.

Jeffrey

[Kosmaj]

Cyrix
You can also consider k=75, it appears to be reasonably populated with primes and it's checked only to n=250k.

My last progress report in 2004:
k=7, [1.1 M]
k=21, [880k]
k=55, [350k]
k=77, 77*2^607920-1 is prime, continuously checked to 575k

I'd also like to cancel k=71 since it's already processed to more than 600k by a third party.

[Harvey563]

I have checked k=91, from 200000 to 210000 & found no primes.
I am checking k=93, from 200000 to 210000. I plan to continue checking whatever k values seem to be unchecked from 200000 to 210000[on the 15k Riesel list.] Please let me know if you've already checked k=93, 95,97,99, 107, 111, ... from 200000 to 210000. Thanks.

Harvey563

[masser]

Hi Harvey,

I'm almost finished testing the following k values over the range n=200K-300K:

k=111, 123, 153, 159, 171, 183, 189, 219, 225

I'll list the results here in a week or so.

Best regards,
masser

[Kosmaj]

Harvey,
Check also the list of searched intervals compiled by Keller. Some people report only to him. While some others report to nobody...

[masser]

Hi all,

Here are some results for several k values:

k=111: 217034, 279227, currently at n=300000
k=123: no new primes to report, currently at n=380000
k=153: no new primes to report, currently at n=300000
k=159: 293235, currently at n=300000
k=171: 259262, 269539, 290403, currently at n=300000
k=183: no new primes to report, currently at n=300000
k=189: 213856, 235068, 237968, 239891, 246356, 255372, currently at n=300000
k=219: no new primes to report, currently at n=300000
k=225: 206293, currently at n=300000

I will continue testing these 9 k-values up to n=400 or 500 K.

best regards,
masser

[Keller]

I would like to reserve k=195 but cant tell how deep I will be able to test it ... I hope to get it to n=500k :)

[Keller]

Yes, that's 195*2^311215-1 found by Shane. It will be nice if he can tell us what range did he checked. On our table currently the limit is 250k, and on Wilfrid Keller's list it's 267k.