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xkcd #3019: Advent Calendar Advent Calendar (xkcd.com)

submitted 2 weeks ago by [email protected] to c/xkcd

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The growth rate of items per day may may seem absurd, but it's actually much less than the acceleration in the 12 Days of Christmas song.

https://explainxkcd.com/3019/

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[–] FilthyShrooms 5 points 2 weeks ago (2 children)

So assuming 25 advent calenders in the advent calender, each with the correct amount of days (1st has 25, 2nd has 24, etc), how many chocolates would there be in total?

[–] Tudsamfa 13 points 2 weeks ago (1 children)

(n*(n+1)/2 = 25*13 =325

Never mind the fact that the "correct" number of days on an advent calender is 24.

[–] Iron_Lynx 2 points 2 weeks ago (1 children)

For one, it looks to me like the triangle numbers, which for triangle number T~n~ = (n+1) choose 2.

So for a correct nested advent calendar of 24 days, it's T~24~ = (24+1) choose 2 = 300

[–] Iron_Lynx 2 points 2 weeks ago* (last edited 2 weeks ago)

Also, it appears that they created the terminal function that does that in a very compact notation, so another correct way to write down this sum is "24?" Where n? = n + (n-1)?

[–] SwordInStone 2 points 2 weeks ago

primary school combinatorics question