  In this study, several interesting iterative sequences were investigated.
First, we define the iterative sequences. We fix function f(n). An iterative
sequence starts with a natural number n, and calculates the sequence
f(n),f(f(n)), ...f(f(f(f(n)))),... We then search for interesting features in
this sequence. We study Kaprekar's routine, the digit factorial process, and
the digit power process. The authors presented new variants of Kaprekar's
routine.
