[seqfan] Re: Sequence A037153

zak seidov zakseidov at yahoo.com
Fri Mar 5 18:08:35 CET 2010


Neil,

btw there's misprint:

n=1..1200

not

n=1..120000

Zak

I'm running (in parallel) Mmca and PARI -
up to n=600 both agree with RM's (and Bob's) data.

Zak


%H A037153 Robert G. Wilson v (rgwv at rgwv.com), <a href="a037153.txt"> Table of n, a(n) for n=1..120000</a> a(n) is the least prime such that n! + p 
               is also prime. 


--- On Fri, 3/5/10, N. J. A. Sloane <njas at research.att.com> wrote:

> From: N. J. A. Sloane <njas at research.att.com>
> Subject: [seqfan] Re: Sequence A037153
> To: seqfan at list.seqfan.eu, seqfan at seqfan.eu
> Cc: njas at research.att.com
> Date: Friday, March 5, 2010, 9:30 AM
> Thanks to people who replied. 
> But I am still worried,
> because 
> 
> >The values in a037153.txt are "basically" correct:
> - the value for n=815 is missing, that is, n=814 is
> followed by n=816,
>   which means values after n=814 are suspicous because
> it is not clear
>   whether there is a slip in the index n or in the
> a(n), or whether n=815 is
>   just completely knocked out.
> 
> This makes me suspicious of the whole file.
> 
> > - At least the first 344 entries of a037153.txt are
> correct,
>   if compared with an equivalent Maple program:
>   http://www.strw.leidenuniv.nl/~mathar/progs/b037153.txt
> (growing...)
> 
> This has now reached 600 or so, so if it still agrees with
> a037153.txt
> up to that point then we can be sure of those values.
> 
> 
> Maybe Bob Wilson could re-do his calculation?  Either
> he
> has a faster machine, or Mma is faster than Maple on this
> problem (or both).
> 
> Bob,  you did not reply to my first message.  Do
> you have
> any comments?  Can you explain why
> there is a gap at n=815?
> 
> Maybe someone else could redo the calculation with mma (up
> to 1200, say)?
> 
> Neil
> 
> 
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