Anyone know how to determine a number is quadratic (perfect squarei don't know what it's called ) or note?
for example:
for $\displaystyle $n \in \mathbb{Z}^{+}$$
proof that $\displaystyle $(n-1)^{2}+(n-2)^{2}+n^{2}+(n+1)^{2}+(n+2)^{2}$$
isn't quadratic number