[seqfan] Re: Highly cototient numbers

[Alonso Del Arte]

Yes, there should be at least one better technique. In 2004, just for the
sake of having a program for
A005277<http://www.research.att.com/~njas/sequences/A005277>,
I sent in a Mathematica program that calculates phi(n) for each n up to 320.
Then in 2006 it finally occurred to me that it would just be easier to
calculate (p - 1)(q - 1) and such and then cull the numbers not in those
sets. Of course the 2004 program can be made to go into larger numbers by
simply changing searchMax, while with the 2006 program one would also have
to take into account totients with more than three prime factors or else be
ready to identify false positives.

Al

On Mon, Mar 15, 2010 at 1:22 AM, Charles Greathouse <
charles.greathouse at case.edu> wrote:

> I was wondering if anyone was up to the task of extending A100827.  It
> seems that there should be much better techniques than just
> calculating the first n^2 cototients -- and it would be nice to see an
> extended graph.  There are a few helpful comments at A063748, but
> these may be well-known and/or obvious.
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
>
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