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 2017-03-22, 03:32 #188 davar55     May 2004 New York City 23×232 Posts Actually I consider the work put into this sequence and the discovery of the a(20) prime very valuable. Perhaps my expectations for an "important result" were already sufficiently satisfied. It certainly is a very interesting anomalously large prime.
2017-03-25, 09:44   #189
J F

Sep 2013

23×7 Posts

Quote:
 Originally Posted by davar55 It certainly is a very interesting anomalously large prime.
What is 'anomalously large'? You can approximate the probability
that the sequence from a starting value will yield no prime up
to some digit count. The chance to 'survive' to 300K digits is
order of magnitude 0.5%. I got 11 >300K with the smallish sample
size of 1666, so far that seems sane enough to me.

 2017-05-19, 13:34 #190 davar55     May 2004 New York City 23·232 Posts Is a(20) longer than 613373?
2017-05-20, 06:27   #191
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

925910 Posts

Quote:
 Originally Posted by davar55 Is a(20) longer than 613373?
613373 has only six digits.
a(20) is definitely longer!

2017-05-23, 13:23   #192
davar55

May 2004
New York City

23×232 Posts

Quote:
 Originally Posted by Batalov 613373 has only six digits. a(20) is definitely longer!
In character length, "a(20)" has only five characters.

But clarifying my question, has a(20) more than 613373 decimal digits?

 2017-06-26, 15:05 #193 davar55     May 2004 New York City 423210 Posts Actually, is a(20) well defined until or unless a prime is found at that location? So the previous post was just a request for a progress report.
 2017-06-26, 22:12 #194 J F     Sep 2013 23×7 Posts Progress report: #20 somewhere around 750K digits, no PRP yet
 2017-06-27, 13:25 #195 davar55     May 2004 New York City 23·232 Posts Thanks. Great work. This result is surprisingly tantalizing.
 2017-06-27, 15:48 #196 ATH Einyen     Dec 2003 Denmark 3·17·59 Posts I stopped at 750k digits searching for "standard" pi primes starting at 3.1415. No new primes before or after the 613373 digit one.
2017-06-27, 16:25   #197
rogue

"Mark"
Apr 2003
Between here and the

2×5×617 Posts

Quote:
 Originally Posted by ATH I stopped at 750k digits searching for "standard" pi primes starting at 3.1415. No new primes before or after the 613373 digit one.
Did you sieve beyond 750k? If so, you should consider posting the remaining terms.

 2017-06-27, 16:33 #198 ATH Einyen     Dec 2003 Denmark BC116 Posts Yes, I sieved up to 1 million digits, and I have actually still been sieving sometimes on computers at work. I'm on vacation now, I will try to sort out how far I got and post in 1-2 weeks.

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