3 numbers

main.py

def get_easy_res(n):
    ans = 0
    for a in range(1, n):
        for b in range(1, n):
            c = n - a - b
            if c <= 0 or a == b or a == c or b == c:
                continue
            ans += 1
    return ans
	
def get_formula_res(n):
    res = ((n-2) * (n-1))//2 - 3 * ((n - 1) // 2)
    if n % 3 == 0:
        res += 2
    return res

for n in range(6, 150):
    er = get_easy_res(n)
    hr = get_formula_res(n)
    if er != hr:
        print('fail', n, er, hr)