Birthday dates using pi continued fractions

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For ? Day. 2015, Wolfram Research stirred up publicity with the blog “Pi or Pie?! Celebrating Pi Day of the Century (And How to Get Your Very Own Piece of Pi)”:

I grumbled that no self-respecting Deity would bother sending clues to worshipers dumb enough to use decimal instead of continued fractions (CF). However, in 2019 we’re barely able to afford a full CF version of Wolfram’s birthday games. Assuming Gauss–Kuzmin distribution, define

Screenshot2019-01-02at16.04.32.png

Then

I.e, 41.5% of terms should be 1, 17% should be 2, etc.
But cfprob also gives us the probabilities of term sequences:

(Invariant under reversal but not shuffling.)

This says to expect about six 1,2,3’s in every burst of 1000 terms:

Screenshot2019-01-02at16.12.49.png

Try a million :

(0.5 seconds for a million terms. Have I actually lived to see this?)

Continued fractions accommodate fancier date formats:

Sure enough, there were two of them.

But for really fancy dates,

Screenshot2019-01-02at16.20.56.png

we’ll need Eric Weisstein’s record ? CF calculation.

Utility functions

These are the definitions of the utility function tim you will need for the above evaluations:

Birthday-Dates-Using-Pi-Continued-Fractions-by-Bill-Gosper.nb (29.8 KB)

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