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Is there any pattern in this (e.g. Once per five years)?
Is it a sliding window?

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  • 1
    $\begingroup$ It's more complicated than that due to leap years among other things. Check out J.H. Conway's Doomsday rule where all your questions should be answered in full detail. $\endgroup$ – t.b. Apr 16 '11 at 8:09
  • $\begingroup$ @Theo Buehler Thanks. Post as an answer and I will accept. I thought it wouldn't be so simple. $\endgroup$ – basarat Apr 16 '11 at 8:20
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Mostly, in cycles of 6, 11, and 11 years. Leap years only repeat every 28 years. See http://wiki.answers.com/Q/How_often_in_years_do_calendars_repeat_with_the_same_day-date_combinations

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It's more complicated than that due to leap years among other things. Check out J.H. Conway's doomsday rule where all your questions should be answered in full detail.

See also the answer and the comments to this related question.

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All depends on the year it starts first birthday after you been born. If your birthday starts on same day , same date, same month. It will take 5 years, 6 years or 11 years which will bring you to your original day of birthday and the sequence never change. Sequence (11 6 5 6 11 6 5 6 11) all depends on which years sequence(5 6 11 6 5 6 11 6 5)or(6 5 6 11 6 5 6 11 6) you start your sequence, but it never change.You can test it yourself and see the consistency of the sequence birthday, same day of the week.

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  • $\begingroup$ The 11-6-5-6 sequence will change if a century year that is not divisble by 400 intervenes, as those years are not leap years. The last such century year was 1900, and the next one will be in 2100. $\endgroup$ – John Sep 30 '17 at 17:25
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I found out: it is a sequence like this every 11-6-5-6-11 years (periodic), 11-6-5-11 years.

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protected by Community Sep 30 '17 at 19:33

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