[seqfan] 1^5+2^5+...+n^5 is a square

[Charles Greathouse]

It was recently asked (on MathOverflow, I think) whether the formula on A031138:

a(n) =11*(a(n-1)-a(n-2)) + a(n-3)

was proved or merely conjectural. Of course it should be proved to be
included as it is, but would someone verify this?

This is of course a 6th-degree Diophantine equation:

12m^2 = n^2 (n+1)^2 (2n^2 + 2n - 1)

Charles Greathouse
Analyst/Programmer
Case Western Reserve University