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Forum: And now for something completely different 2017-11-20, 14:02
Replies: 22
Views: 15,813
Posted By ericw
(Actually 260448 decimal digits.) ...

(Actually 260448 decimal digits.)

Congratulations again :)
Forum: And now for something completely different 2017-08-11, 14:47
Replies: 22
Views: 15,813
Posted By ericw
https://oeis.org/A100289 Numbers n such that...

https://oeis.org/A100289
Numbers n such that (1!)^2 + (2!)^2 + (3!)^2 +...+ (n!)^2 is prime.
a(19) = 32841 from Serge Batalov, Jul 29 2017
Forum: And now for something completely different 2017-02-20, 12:13
Replies: 27
Views: 6,523
Posted By ericw
Cool. Thanks for the update!

Cool. Thanks for the update!
Forum: And now for something completely different 2017-02-02, 15:23
Replies: 27
Views: 6,523
Posted By ericw
FWIW, back on 2009-06-03, I used Mathematica to...

FWIW, back on 2009-06-03, I used Mathematica to show

PrimeQ[FromDigits[First[RealDigits[GoldenRatio, 10, 97241]]]]
True

See http://mathworld.wolfram.com/IntegerSequencePrimes.html (under...
Forum: And now for something completely different 2016-06-20, 01:55
Replies: 32
Views: 8,458
Posted By ericw
Thanks again for your hunting and for the...

Thanks again for your hunting and for the updates! Will update MathWorld.
Forum: And now for something completely different 2016-04-11, 14:43
Replies: 32
Views: 8,458
Posted By ericw
Thanks again. Small clarification: does that mean...

Thanks again. Small clarification: does that mean you have *already* reached 465,000 and have now stopped, or that you expect to do so soon? (Basically, should I update MathWorld yet.)
Forum: And now for something completely different 2016-02-15, 12:52
Replies: 32
Views: 8,458
Posted By ericw
Cool. Thanks again for continuing the search and...

Cool. Thanks again for continuing the search and providing an update on your progress!
Forum: And now for something completely different 2016-01-18, 17:05
Replies: 32
Views: 8,458
Posted By ericw
Thanks for the update, Mark. Will update...

Thanks for the update, Mark. Will update MathWorld.
Forum: And now for something completely different 2015-12-21, 13:56
Replies: 32
Views: 8,458
Posted By ericw
32 CPU-hours on moderately old hardware. (PrimeQ...

32 CPU-hours on moderately old hardware. (PrimeQ uses a multiple Rabin-Miller test in bases 2 and 3 combined with a Lucas pseudoprime test.)
Forum: And now for something completely different 2015-12-17, 11:50
Replies: 32
Views: 8,458
Posted By ericw
Verified also using Mathematica's PrimeQ (returns...

Verified also using Mathematica's PrimeQ (returns True -> probable prime)

Congratulations!
Forum: And now for something completely different 2015-12-08, 14:54
Replies: 32
Views: 8,458
Posted By ericw
Thanks for posting these updates Mark. ...

Thanks for posting these updates Mark. Unfortunately, I am still having a problem understanding your limits. Concatenating all primes < 550,000 gives an integer with

In[4]:= Total[IntegerLength...
Forum: And now for something completely different 2015-11-20, 14:02
Replies: 32
Views: 8,458
Posted By ericw
(FWIW, https://oeis.org/A227530 gives the decimal...

(FWIW, https://oeis.org/A227530 gives the decimal digit lengths of Copland-Erdos constant primes.)
Forum: And now for something completely different 2015-11-20, 14:01
Replies: 32
Views: 8,458
Posted By ericw
By any chance should that be "all primes <...

By any chance should that be "all primes < 30,000"?

In[6]:= Total[IntegerLength[Prime[Range[30000]]]]
Out[6]= 168982
Forum: And now for something completely different 2015-11-10, 15:55
Replies: 21
Views: 3,630
Posted By ericw
Nice. I will update MathWorld. Do you care to...

Nice. I will update MathWorld. Do you care to polish off 48250 to 49999 while you're at it (since clearly your search will finish way before mine gets there).
Forum: And now for something completely different 2015-11-03, 18:32
Replies: 21
Views: 3,630
Posted By ericw
Perfect. Thank you.

Perfect. Thank you.
Forum: And now for something completely different 2015-11-03, 14:18
Replies: 21
Views: 3,630
Posted By ericw
Indeed. Another question for Paul or anyone else...

Indeed. Another question for Paul or anyone else (I am having trouble rejoining primeform on Yahoo groups to ask there.) I see PrimeGrid has been busily finding new Thabit ibn Kurrah primes 3*2^n -...
Forum: And now for something completely different 2015-11-03, 12:13
Replies: 21
Views: 3,630
Posted By ericw
Thanks. Yes, still searching. As of...

Thanks.



Yes, still searching. As of today the search has reached 47889 47888 ... 3 2 1 without finding any more PRPs.
Forum: And now for something completely different 2015-11-02, 16:04
Replies: 21
Views: 3,630
Posted By ericw
p#-1 and OEIS A057704

It seems https://oeis.org/A057704

2, 3, 5, 6, 13, 24, 66, 68, 167, 287, 310, 352, 564, 590, 620, 849, 1552, 1849

misses recently found large p#-1 primes; cf. e.g....
Forum: And now for something completely different 2015-11-02, 15:53
Replies: 21
Views: 3,630
Posted By ericw
Yes, the comment in question applied to the 1st...

Yes, the comment in question applied to the 1st edition but the reference got updated to the 2nd edition, where it no longer applies. Fixed on...
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