[seqfan] Re: A006451 = n such that n*(n+1)/2+1 is square?

Richard Mathar mathar at strw.leidenuniv.nl
Sat Oct 10 20:36:40 CEST 2009


ma> Date: Sat, 10 Oct 2009 11:46:36 -0400
ma> From: Max Alekseyev <maxale at gmail.com>
ma> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
ma> Subject: [seqfan] Re: A006451 = n such that n*(n+1)/2+1 is square?
ma> 
ma> Representation of primes by quadratic forms is well-studied subject.
ma> Even is SeqFan we discussed it several times.
ma> There cannot be any conjectures. ;)


Can the question in A141131 about the equivalence of the primes of this
particular quadratic form be answered:

http://research.att.com/~njas/sequences/A141131
http://research.att.com/~njas/sequences/A038873

A conjecture in the same category is formulated in A033212

There is another equivalence in doubt here:
http://research.att.com/~njas/sequences/A141158
http://research.att.com/~njas/sequences/A038872

or here
http://research.att.com/~njas/sequences/A141174
http://research.att.com/~njas/sequences/A007519

Others of that kind can be found if one fishes for the Caballero Fernandez
submissions in the middle of 2008 or scans the list of duplicate candidates
in http://www.strw.leidenuniv.nl/~mathar/progs/oeisDupl around A141178 .

RJM




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