'''
((a - 1) ** n + (a + 1) ** n) % (a ** 2) =
2an % (a ** 2), if n is odd; 2, if n is oven
'''

def pre_odd(q):
    n = int(q)
    if n == q:
        return n - (1 + n % 2)
    else:
        return n - (1 - n % 2)

def r_max(a):
    return max(map(lambda n: 2 * a * n % (a ** 2),
                map(lambda x: pre_odd(x), [a / 2, a, 3 * a / 2, 2 * a])))

print(sum(map(lambda x: r_max(x), range(3, 1001))))