from functools import lru_cache


@lru_cache
def count(days_left, absent_count):
    if absent_count > 1:
        return 0
    if days_left == 0:
        return 1
    if days_left < 0:
        return 0
    c = 0
    c += count(days_left - 1, absent_count + 1) # "a"
    c += count(days_left - 2, absent_count + 1) # "la"
    c += count(days_left - 3, absent_count + 1) # "lla"

    c += count(days_left - 1, absent_count)     # "o"
    c += count(days_left - 2, absent_count)     # "lo"
    c += count(days_left - 3, absent_count)     # "llo"

    if days_left == 2:
        c += 1 # "ll"

    if days_left == 1:
        c += 1 # "l"

    return c


def euler_191():
    return count(30, 0)


if __name__ == "__main__":
    solution = euler_191()
    print("e191.py: " + str(solution))
    assert(solution == 1918080160)