mersenneforum.org Thread for posting tiny primes
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 2010-12-12, 21:00 #903 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 942610 Posts 1512500-82 is prime-in-progress.
 2010-12-12, 21:06 #904 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 2×3×1,571 Posts (38ยท1017876-29)/9 is a prime (17877 digits)
 2010-12-13, 10:03 #905 lorgix     Sep 2010 Scandinavia 26716 Posts Is anyone keeping track of compositorials?
2010-12-14, 01:16   #906
3.14159

May 2010
Prime hunting commission.

168010 Posts

Quote:
 Originally Posted by lorgix Is anyone keeping track of compositorials?
The products of the first few composite numbers? Not that I'm aware of. You can get started on those.

Is that n!/n#?

Last fiddled with by 3.14159 on 2010-12-14 at 01:16

2010-12-14, 01:42   #907
science_man_88

"Forget I exist"
Jul 2009
Dumbassville

26×131 Posts

Quote:
 Originally Posted by 3.14159 The products of the first few composite numbers? Not that I'm aware of. You can get started on those. Is that n!/n#?
http://oeis.org/A036691 by the looks of it.

first result they don't have is :

101 3789610361627996838140194973640931105417226023081643585822775079629508916741315290850885175293649036474831772927007647018057857770220427674522746880000000000000000000000000000000

by the looks of it.

Last fiddled with by science_man_88 on 2010-12-14 at 02:02

 2010-12-14, 04:26 #908 CRGreathouse     Aug 2006 32·5·7·19 Posts If you like you can submit a b-file with more terms. I don't usually send in b-files for easy sequences unless there's special interest for some reason (for example, with plot2). You may find this useful: http://oeis.org/wiki/User:Charles_R_...g_with_b-files
2010-12-14, 06:30   #909
lorgix

Sep 2010
Scandinavia

3·5·41 Posts

Quote:
 Originally Posted by 3.14159 The products of the first few composite numbers? Not that I'm aware of. You can get started on those. Is that n!/n#?
I guess I could have been more clear; compositorial primes.

So; n!/n# +/- 1

Like

2967!/2967#-1 (7753digits)
2532!/2532#-1 (6453digits)

factordb has tables for n!/n# +/- 1
http://factorization.ath.cx/tables.php?open=8

2010-12-14, 13:45   #910
science_man_88

"Forget I exist"
Jul 2009
Dumbassville

26·131 Posts

Quote:
 Originally Posted by lorgix I guess I could have been more clear; compositorial primes. So; n!/n# +/- 1 Like 2967!/2967#-1 (7753digits) 2532!/2532#-1 (6453digits) factordb has tables for n!/n# +/- 1 http://factorization.ath.cx/tables.php?open=8
http://oeis.org/A093155 is part of the -1 side.
http://oeis.org/search?q=2,5,193&sor...lish&go=Search is the best I can get for the +1 side

Last fiddled with by science_man_88 on 2010-12-14 at 13:46

2010-12-14, 16:15   #911
CRGreathouse

Aug 2006

32×5×7×19 Posts

Quote:
 Originally Posted by lorgix I guess I could have been more clear; compositorial primes.
Ah. Those are indexed by Sloane's A049420 and A049421.

2010-12-14, 16:55   #912
lorgix

Sep 2010
Scandinavia

3·5·41 Posts

Quote:
 Originally Posted by CRGreathouse Ah. Those are indexed by Sloane's A049420 and A049421.
Thanks.

Oh, so all smaller than 10000digits.

n= 3692 for the +1s, 3337 for the -1s.

 2010-12-24, 07:22 #913 lorgix     Sep 2010 Scandinavia 3×5×41 Posts Come on, that can't be it. Does anyone know any bigger ones? Unrelated matter: Is anyone factoring 17^n+1?

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