41, 80 and 320?
If you add the three numbers you get a perfect square:
$\displaystyle 41 + 80 + 320 = 441 = 21^2$
And... if you add any two of the numbers you also get perfect squares:
$\displaystyle \begin{aligned}
41 + 80 &= 121 = 11^2 \\
80 + 320 &= 400 = 20^2 \\
41 + 320 &= 361 = 19^2
\end{aligned}$
If it wasn't for Soroban's last post I wouldn't have thought of this.