Question 55
Find all positive odd integers $n$ for which there exist odd integers $x_1, x_2, \dots, x_n$ such that
$$
x_1^2 + x_2^2 + \dots + x_n^2 = n^4.
$$
$$
x_1^2 + x_2^2 + \dots + x_n^2 = n^4.
$$
MathNet 2007-part-03 — 185 problems (EN–VI) Question 55
Math Olympiad Vault · MathNet 2007-part-03 — 185 problems (EN–VI)