[seqfan] Re: A139442

Charles Greathouse charles.greathouse at case.edu
Thu Jun 13 23:32:10 CEST 2013


I get
3, 4, 7, 9, 10, 11, 13, 15, 22, 23, 29, 45, 51, 52, 55, 69, 98, 122, 157,
268, 367, 476, 481, ...
with
is(n)=ispseudoprime(prod(i=2,n,prime(i))-8)

The inclusion of 2 is presumably due to a different definition of "prime".

Charles Greathouse
Analyst/Programmer
Case Western Reserve University


On Thu, Jun 13, 2013 at 4:49 PM, Harvey P. Dale <hpd at hpdale.org> wrote:

>         I get quite different terms for the above sequence.  My terms
> agree with the first three terms; then I find an additional term not now in
> the sequence; thereafter, my terms are almost (but not quite) always one
> greater than the terms in the sequence currently.  It seems to me to be
> primarily an index disagreement.
>
>         Here is my Mma program:
>
>
> With[{pms=FoldList[Times,1,Prime[Range[500]]]},Flatten[Position[pms,_?(PrimeQ[#/2-8]&)]]]
>
>         If the program and the sequence terms could be checked, I'll be
> glad to update the sequence accordingly.
>
>         Best,
>
>         Harvey
>
>
>
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