Introduced by Michael Keith in 1987, Keith Numbers (also known as repfigit numbers or repfigits from repetitive Fibonacci-like digit) can be described:

A Keith Number is a n digit integer N with the following property: If a Fibonacci-like sequence (in which each term in the sequence is the sum of the previous n terms) is formed, with the first n terms being the decimal digits of the number N, then N itself occurs as a term in the sequence.
The On-Line Encyclopedia of Integer Sequences gives 197 as an example:

1, 9, 7, 17, 33, 57, 107, 197, ...

According to Michael Keith, there are only 71 Keith Numbers less than 1019.

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