The Least Number with Prescribed Legendre Symbols
  In this article we estimate the number of integers up to $X$ which can be represented by a positive-definite, binary integral quadratic form of discriminant which is small relative to $X$. This follows from understanding the vector of signs when computing the Legendre symbol of small integers $n$ at multiple primes. 
Brandon Hanson, Robert C. Vaughan, Ruixiang Zhang
math.NT