from math import prod, comb
from fractions import Fraction


a, n = 3, 10

def loi(a, n):
    return [Fraction(comb(n- k, n - a - 1), comb(n,a)) for k in range(1, a + 2)]

l = loi(3, 10)
m = sum((k + 1)* x for k, x in enumerate(l))
v = sum((k + 1)**2* x for k, x in enumerate(l))- m**2
print(loi(3, 10))
print(m, v)