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2018-08-09, 23:24   #1
Dylan14

"Dylan"
Mar 2017

1110101002 Posts
Primes in e

Following the threads regarding primes in pi (http://www.mersenneforum.org/showthread.php?t=16978) and phi (http://www.mersenneforum.org/showthread.php?t=21942), I have decided to start a thread looking for primes in e. I have attached the first million digits of e to the end of this post.

Like for pi and phi, there are two parts to the search:
1) Take the decimal expansion of e and locate primes in it, starting with the 2.
2) For each positive integer n, locate in the decimal expansion of e the first occurrence of the digits of the integer n, and then find the first prime constructed from the subsequent digits of e.

I am in the process of sieving 1) for the first million decimal digits of the expansion and I intend on testing that form in the hopes of finding a new e prime and to verify that none have been missed up to the current search limit (which is 197760 according to http://mathworld.wolfram.com/IntegerSequencePrimes.html although that status is from 2016). Is anyone interested in doing the second part?
Attached Files
 e_1M.txt (976.6 KB, 50 views)

 2018-08-10, 00:59 #2 rogue     "Mark" Apr 2003 Between here and the 3×11×173 Posts Here is the OEIS sequence for primes starting with the first digit of e. With a small modification to pixsieve to output primes that it finds, there are only 2 starting terms < 100 with no primes under 1000 digits. 33 has a prime of length 1507. 42 has one of length 1470.
 2018-08-10, 03:31 #3 CRGreathouse     Aug 2006 586010 Posts http://oeis.org/A064118 is the main sequence.
 2018-08-10, 06:07 #4 LaurV Romulan Interpreter     Jun 2011 Thailand 100001010110102 Posts [mod hat on] We are tempted to remove the big text attach, but let's ask first... Maybe we are worrying in vain, but you are wasting forum space and more important, wasting your attachments quota too... At least, it could be zipped, being only numbers it has a very good compression ratio. Usually, people who join such effort are very much able to generate it with pari (just a simple command), or other tools, in (milli)seconds, or get it from web. [mod hat off] Last fiddled with by LaurV on 2018-08-10 at 06:10
2018-08-10, 15:10   #5
CRGreathouse

Aug 2006

22×5×293 Posts

Quote:
 Originally Posted by LaurV Usually, people who join such effort are very much able to generate it with pari (just a simple command), or other tools, in (milli)seconds, or get it from web.
I can't really imagine someone being able to productively contribute to such a search, and yet being unable to generate the digits of e. YMMV.

2018-08-10, 15:28   #6
rogue

"Mark"
Apr 2003
Between here and the

3·11·173 Posts

Quote:
 Originally Posted by CRGreathouse http://oeis.org/A064118 is the main sequence.
I know, but I don't see any real value in a sequence of "decimal length of primes" although I could see one argue that the primes themselves aren't very important either. Nevertheless, computing the decimal length of a PRP/prime is a no-brainer and a lot of sequences like this seem to clutter OEIS.

2018-08-10, 15:37   #7
Dylan14

"Dylan"
Mar 2017

22·32·13 Posts

Quote:
 Originally Posted by LaurV We are tempted to remove the big text attach, but let's ask first... Maybe we are worrying in vain, but you are wasting forum space and more important, wasting your attachments quota too... At least, it could be zipped, being only numbers it has a very good compression ratio. Usually, people who join such effort are very much able to generate it with pari (just a simple command), or other tools, in (milli)seconds, or get it from web.
The only reason why I put the digits of e is simply just for convience for those who want to partake in the search. Although it is quite easy to generate them (y-cruncher generates the first million digits in about 2 tenths of a second on my hardware) and to find them on the web (a quick google search for decimal digits of e gives two links on the top of the results, one with 10k digits and one with 2M digits). If it is that much of a bother, feel free to remove the attachment.

2018-08-10, 16:59   #8
CRGreathouse

Aug 2006

133448 Posts

Quote:
 Originally Posted by rogue I know, but I don't see any real value in a sequence of "decimal length of primes" although I could see one argue that the primes themselves aren't very important either. Nevertheless, computing the decimal length of a PRP/prime is a no-brainer and a lot of sequences like this seem to clutter OEIS.
The primes can be better for findability, the lengths are better for communication. Personally I can't get excited about either, I don't like base sequences.

 2018-08-23, 15:33 #9 Dylan14     "Dylan" Mar 2017 22×32×13 Posts I have tested to 100,000 digits and confirmed all primes/PRP's up to that point. No primes/PRP's were missed. Continuing.
 2018-10-11, 00:55 #10 Dylan14     "Dylan" Mar 2017 22·32·13 Posts I have tested to 200,000 digits and confirmed all primes/PRP's up to the old search limit of 197760. No primes were missed. Above the search limit, I found no new primes. Continuing. Question: Is there a standard notation for designating an e prime? I ask since on http://www.primenumbers.net/prptop/prptop.php, primes in pi are denoted by PIPrime(n), where n is an integer.
 2018-10-11, 01:29 #11 Batalov     "Serge" Mar 2008 Phi(3,3^1118781+1)/3 52·192 Posts floor(e*10^N)

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