The convolution sum ∑m<n/16σ(m)σ(n - 16m) is evaluated for all n ∈ ℕ. This evaluation is used to determine the number of representations of n by the quadratic form x1 2 + x2 2 + x3 2 + x4 2 + 4x5 2 + 4x6 2 + 4x 7 2 + 4x8 2.