Keith number

A Keith number is a type of integer that relates to sequences derived from the digits of a number. Given a positive integer \( n \), it is represented in its decimal form. The digits of \( n \) are used to create a sequence where the first terms are derived from the digits of \( n \) and each subsequent term is the sum of the last \( d \) terms, where \( d \) is the number of digits in \( n \).