from math import comb

def aux_q11(n):
    soma = 0
    for i in range(n+1):
        soma += i * comb(n,i)
    return soma

def investiga_q11(limite=20):
    for n in range(limite):
        print(f"{n} -> {aux_q11(n)}")

def q9(n):
    soma = 0
    for k in range(1,n//2 + 1):
        soma += (n/k)*comb(n-k-1,k-1)
    return soma