Lagrange's four-square theorem - Wikipedia

数论代考, 四平方和定理The four square theorem 代写

PDF) Lagrange's Four-Square Theorem

Euler's four-square identity

Jacobi's four-square theorem - Wikipedia

Lagrange's four-square theorem - Wikiwand

SOLVED: Theorem 8.35 (Lagrange's Four-Square Theorem) then n can be expressed as the sum If n is a number; of four squares: natural lattice A in 4-space is a set of the

Lagrange's Four Square Theorem

Sum of two squares theorem - Wikipedia

Sum of squares, Part-2, Sum of four squares

Euler Four-Square Identity -- from Wolfram MathWorld