English

Sequences of consecutive factoradic happy numbers

Number Theory 2019-12-05 v1

Abstract

Given a positive integer nn, the factorial base representation of nn is given by n=i=1kaii!n=\sum_{i=1}^ka_i\cdot i!, where ak0a_k\neq 0 and 0aii0\leq a_i\leq i for all 1ik1\leq i\leq k. For e1e\geq 1, we define Se,!:Z0Z0S_{e,!}:\mathbb{Z}_{\geq0}\to\mathbb{Z}_{\geq0} by Se,!(0)=0S_{e,!}(0) = 0 and Se,!(n)=i=0naieS_{e,!}(n)=\sum_{i=0}^{n}a_i^e, for n0n \neq 0. For 0\ell\geq 0, we let Se,!(n)S_{e,!}^\ell(n) denote the \ell-th iteration of Se,!S_{e,!}, while Se,!0(n)=nS_{e,!}^0(n)=n. If pZ+p\in\mathbb{Z}^+ satisfies Se,!(p)=pS_{e,!}(p)=p, then we say that pp is an ee-power factoradic fixed point of Se,!S_{e,!}. Moreover, given xZ+x\in \mathbb{Z}^+, if pp is an ee-power factoradic fixed point and if there exists Z0\ell\in \mathbb{Z}_{\geq 0} such that Se,!(x)=pS_{e,!}^\ell(x)=p, then we say that xx is an ee-power factoradic pp-happy number. Note an integer nn is said to be an ee-power factoradic happy number if it is an ee-power factoradic 11-happy number. In this paper, we prove that all positive integers are 11-power factoradic happy and, for 2e42\leq e\leq 4, we prove the existence of arbitrarily long sequences of ee-power factoradic pp-happy numbers. A curious result establishes that for any e2e\geq 2 the ee-power factoradic fixed points of Se,!S_{e,!} that are greater than 11, always appear in sets of consecutive pairs. Our last contribution, provides the smallest sequences of mm consecutive ee-power factoradic happy numbers for 2e52\leq e\leq 5, for some values of mm.

Keywords

Cite

@article{arxiv.1912.02044,
  title  = {Sequences of consecutive factoradic happy numbers},
  author = {Joshua Carlson and Eva G. Goedhart and Pamela E. Harris},
  journal= {arXiv preprint arXiv:1912.02044},
  year   = {2019}
}

Comments

10 pages, 3 tables, 1 figure

R2 v1 2026-06-23T12:35:45.659Z