Problem 644

Every Day is a Holiday

Problem 646

Every Day is a Holiday

Problem 645

On planet J, a year lasts for days. Holidays are defined by the two following rules.
  • At the beginning of the reign of the current Emperor, his birthday is declared a holiday from that year onwards.
  • If both the day before and after a day are holidays, then also becomes a holiday.
  • Initially there are no holidays. Let be the expected number of Emperors to reign before all the days of the year are holidays, assuming that their birthdays are independent and uniformly distributed throughout the days of the year.
    You are given , , .
    Find . Give your answer rounded to 4 digits after the decimal point.