In which Brain teaches Pinky his numbers

Brain begins Pinky's first math lesson by writing "1" on the blackboard, asking "Pinky, do you know what this is?" Pinky responds, "YEP! It's one one!" Brain slaps himself on the forehead. "No Pinky, 'one one' is like this," he writes "11" on the board. "And it's called eleven." Pinky looks confused, "But that's two one..." he says. Brain writes "21" on the board, but before he can speak, Pinky continues, "And that's one two and one one." So Brain writes "1211." Pinky cuts in, "...and that's one one, one two, and two one!" Brain writes "111221"...

If the conversation and blackboard work continues in this fashion, in what number will Brain write the first 4?

11321321141 312211411122 Brain will never write a 4 1112313241 1413112221

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1 solution

Sylvain Pelloquin
Sep 13, 2015

This is the Conway suite. Basically, you can't have a 4 because that would mean four identical numbers in the previous line, like 1111, 2222... But this is impossible. http://eljjdx.canalblog.com/archives/2015/06/29/32278826.html

Except I can't read french.

Wonseok Song - 5 years, 4 months ago

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You can read it here on Brilliant (It's in the paragraph "Rules for Creating the Sequence")

Henry U - 2 years, 6 months ago

Basically 1111 would mean 11 which would be written 21.

B Martin - 1 year, 6 months ago

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