Quadratic Polynomial Happy Functions

Document Type

Article

Publication Title

Rocky Mountain Journal of Mathematics

Publication Date

2023

Abstract/ Summary

Fix a base b and a monic quadratic polynomial function f with nonnegative coefficients. The corresponding quadratic polynomial happy function maps any positive integer to the sum of the images under f of its nonzero digits. We study the behavior of these functions under iteration. Our main result is that for b ≥ 4, given any fixed point or element of a cycle under iterations of this happy function, there exist arbitrarily long arithmetic sequences of positive integers each of which eventually maps to that number. This extends past results for generalized happy functions in a new direction.

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