[seqfan] Re: Gregg Whisler's sequences A178793, A178794, A216467

[Charles Greathouse]

A comment claims
a(n) is also A157428 + 1.
that is,
A178793(n) = A157428 + 1.

But this can't be right, since (1308, 1274) is in (A157428, A157429)
but not in (A178793, A178794).

> I marked A216467 as "conjectural", because I am not
> sure how many of these terms are known to be correct. Could there be an
> isolated
> visible point with coordinates (19,66567788765), say, which would imply
> that 19 is also in the sequence?

I see no reason there couldn't be. Well, not 19 -- the coordinates
must be composite. But for numbers with (x-1, x, x+1) divisible by
sufficiently many primes it should be possible to construct a (large)
solution.

I would order such a sequence by L1 distance from the origin (then
lexicographically).

Charles Greathouse
Analyst/Programmer
Case Western Reserve University

On Wed, Oct 17, 2012 at 2:49 PM, Neil Sloane <njasloane at gmail.com> wrote:
> Dear Seq Fans,
> Gregg Whisler's sequence A216467 has been languishing at the bottom of the
> "editing" stack for some time. It seems to be an interesting question in
> number theory,
> so I approved it. It is related to four other sequences, A157428, A157429,
> A178793, A178794.
>
> I marked A216467 as "conjectural", because I am not
> sure how many of these terms are known to be correct. Could there be an
> isolated
> visible point with coordinates (19,66567788765), say, which would imply
> that 19 is also in the sequence?
> Should A178793, A178794 also be marked as conjectural?
>
> Neil
>
> Copy to Eric Rowland, who contributed a program to A178793, in case he is
> not a member of this list
>
> --
> Dear Friends, I have now retired from AT&T. New coordinates:
>
> Neil J. A. Sloane, President, OEIS Foundation
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
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