Question 105
Determine all prime numbers $a, b, c$ and nonzero natural numbers $k$ that satisfy the equality
$$
a^{2}+b^{2}+16 c^{2}=9 k^{2}+1
$$
$$
a^{2}+b^{2}+16 c^{2}=9 k^{2}+1
$$
MathNet 2015-part-04 — 191 problems (EN–VI) Question 105
Math Olympiad Vault · MathNet 2015-part-04 — 191 problems (EN–VI)