MathDB

7

Part of 2005 Switzerland - Final Round

Problems(1)

7 x4^n = a^2 + b^2 + c^2 + d^2

Source: Switzerland - 2005 Swiss MO Final Round p7

12/26/2022
Let n≥1n\ge 1 be a natural number. Determine all positive integer solutions of the equation 7⋅4n=a2+b2+c2+d2.7 \cdot 4^n = a^2 + b^2 + c^2 + d^2.
diophantineDiophantine equationnumber theory