def euler_346():
    n_max = 10**12
    repunits = set()
    result = 1  # Our algorithm doesn't catch 1 so we add it here
    for base in range(2, n_max):
        n = base ** 0 + base ** 1
        for exp in range(2, n_max):
            n += base**exp
            if exp == 2 and n > n_max:
                # There are no more repunits below n_max.
                return result
            if n >= n_max:
                break
            if not n in repunits:
                repunits.add(n)
                result += n


if __name__ == "__main__":
    solution = euler_346()
    print("e346.py: " + str(solution))
    assert(solution == 336108797689259276)