[seqfan] Re: A056619

Neil Sloane njasloane at gmail.com
Wed Feb 22 02:04:36 CET 2017

Robert,  Thanks for catching that error in A056619.
I guess 17 years is long enough to give it a permanent place in the OEIS,
even if it is wrong. So what I suggest is, you create a new and correct
version, and change the name of A056619 to "Erroneous version of [new
A-number]", and change the link in A023049 to point to the new version.

Fortunately that seems to be the only OEIS link to the bad version.

Best regards

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com

On Tue, Feb 21, 2017 at 3:49 PM, <israel at math.ubc.ca> wrote:

> A056619 is "Smallest prime with primitive root of n or 0 if no such prime
> exists." In the Crossrefs (what should probably be a Comment) says:
> Here the primitive root may be larger than the prime, whereas in A023049
> in may not be.
> and the Comment says:
> a(n) = 0 only for perfect squares, A000290.
> The Data has a(n) = 0 for squares < 99.
> Well, I agree with that for even n, because if p is an odd prime a square
> can't be a primitive root mod p. But I see no reason for that to be true
> for odd n: all odd numbers, including odd squares, are primitive roots mod
> 2. So I think a(n) should be 2, not 0, for odd squares.
> However, this being an old sequence, I hesitate to change the Data.  What
> do
> you suggest?
> Cheers,
> Robert
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