Ternary positive quadratic forms that represent all odd positive integers
Under the assumption that the ternary form x² + 2y² + 5z² + xz represents all odd positive integers, we prove that a ternary quadratic form ax² + by² + cz² (a,b,c ∈ ℕ) represents all positive integers n ≡ 4(mod 8) if and only if it represents the eight integers 4,12,20,28,52,60,140 and 308.
In this paper some properties of quadratic forms whose base points lie in the point set , the fundamental domain of the modular group, and transforming these forms into the reduced forms with the same discriminant are given.