[seqfan] Re: Jacobsthal function

[allouche at math.jussieu.fr]

Hi
Does the following help?
http://www.ams.org/journals/mcom/2009-78-266/S0025-5718-08-02166-2/S0025-5718-08-02166-2.pdf

best
jp


Charles Greathouse <charles.greathouse at case.edu> a écrit :

> The Jacobsthal function, A048669, is an important sequence which
> appears in many contexts (e.g., bounding the size of prime gaps;
> finding the least prime in an arithmetic progression; bounding the
> state complexity of regular languages). It is defined as the maximal
> distance between numbers relatively prime to n.
>
> How is it computed? The sequence is marked easy, and yet the only
> program listed is very slow, doing calculations on all numbers up to
> n.
>
> A search reveals a body of literature on computing A048670 =
> a(prime(n)#) efficiently, but nothing on the sequence itself. Perhaps
> it is obvious but I can't immediately see it.
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
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