Sum[Floor[(a*i^2+b*i+c)/m], {i, 1, n}] in closed algebraic form and output.

def summation(a, b, c, m, n):
    res = 0
    for i in range(1, n + 1):
        res += floor((a * i * i + b * i + c) / m)
    return res

summation(2, 3, 4, 5, 6)