How to use Wolfram|Alpha to calculate Friday the 13ths I know someone born on the 13th and we were talking about how Friday the 13th is his birthday from time to time. I thought that might be a good question for Wolfram|Alpha but no matter how I phrase it I can't get it right.
I've (unsuccessfully) tried


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*Fridays which are the 13th of June

*Next 100 Fridays and are in June

*List of Friday the 13ths

*List of days

*Today is Friday?


What's (kinda) worked


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*First Friday next month (correct)

*13th next month (Interpreted as "Thursday next month"

*First Friday in next year (correct)

*13th day of this month (correct)


Based on that working entries, I tired these, none of which worked:


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*{Each, Every, All, List of} Friday in next year

*(13th in next month) and (Friday)


You can compute it using a perpetual calenda r http://en.wikipedia.org/wiki/Perpetual_calendar : basically, re the issue of what day falls in which date, there are , for our Western calendar, just 14 possible arrangements of day vs. date: the 1st day of the year can be either Monday, Tuesday,..., Sunday, and the year can be a leap year or non-leap year. Once you know what day January 1st fell on your frinds birth year, you can figure it out.
