[seqfan] Re: three triangular numbers in a row
guninski at guninski.com
Fri Jun 24 08:31:20 CEST 2011
On Fri, Jun 24, 2011 at 01:58:37PM +1000, Brendan McKay wrote:
> A question related to A075528 and A061278 was asked at
> It is equivalent to:
> Is there any n such that n, 2n, and 3n are all triangular numbers?
I would recommend the question to be asked on http://math.stackexchange.com/
Might help to add that over the rationals the equations define an elliptic curve so it boils down to finding the integral points.
I tried to solve it, but can't get a Weierstrass model (for the group law) because of a program bug...
Possibly the OP disallows non-positive n because of (0,0,-1).
More information about the SeqFan