def investment(PMT, n, i):
    investment_balance = 0
    for x in range(0, n):
        if x % 2 == 1:
            PMT = 2 * PMT
        investment_balance *= (1 + i)
        investment_balance += (PMT)

    return round(investment_balance, 2)


print(investment(10000, 40, 0.1045) == 41728281751.16)
print(investment(15000, 30, 0.1045) == 1954935238.47)