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Keith Numbers - Numberphile

2012-11-13

[public] 181K views, 3.59K likes, 37.0 dislikes audio only

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Professor Copeland on Keith numbers, clusters and "reverse Keiths".

More links & stuff in full description below ↓↓↓

And before commenting on the merits of "recreational maths" - hear what Ed says. Ed tweets at https://twitter.com/ProfEdCopeland

Keith Numbers are also known as repfigit numbers (repetitive Fibonacci-like digit).

We also spoke with Mike Keith about his numbers and he issued a playful challenge:

"There are many variations on this idea that you can imagine. For example, for a 3-digit number, instead of the next term being a+b+c (a,b,c being the three previous terms) it could be a+2b+3c, or a^2 + b + c or even more fancifully, 2a + b + the cth prime number. You could think up your own version, and name it after yourself!"

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Example Two Digit Numbers
/youtube/video/uuMwz47LV_w?t=129.5
Example of a Reverse Keith Number
/youtube/video/uuMwz47LV_w?t=242.06
An Example of a Keith Cluster
/youtube/video/uuMwz47LV_w?t=321.89999