Introduced by

Michael Keith in 1987,

Keith Numbers (also known as

repfigit numbers or

repfigits from

**rep**etitive **Fi**bonacci-like di**git**) 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 10^{19}.