English

Sequences of Consecutive Happy Numbers in Negative Bases

Number Theory 2017-05-15 v1

Abstract

For b2b\leq -2 and e2e \geq 2, let Se,b:ZZ0S_{e,b}:\mathbb{Z}\to\mathbb{Z}_{\geq 0} be the function taking an integer to the sum of the ee-powers of the digits of its base bb expansion. An integer aa is a bb-happy number if there exists kZ+k\in\mathbb{Z}^+ such that S2,bk(a)=1S_{2,b}^k(a) = 1. We prove that an integer is 2-2-happy if and only if it is congruent to 1 modulo 3 and that it is 3-3-happy if and only if it is odd. Defining a dd-sequence to be an arithmetic sequence with constant difference dd and setting d=gcd(2,b1)d = \gcd(2,b - 1), we prove that if b3b \leq -3 odd or b{4,6,8,10}b \in \{-4,-6,-8,-10\}, there exist arbitrarily long finite sequences of dd-consecutive bb-happy numbers.

Keywords

Cite

@article{arxiv.1705.04648,
  title  = {Sequences of Consecutive Happy Numbers in Negative Bases},
  author = {Helen G. Grundman and Pamela E. Harris},
  journal= {arXiv preprint arXiv:1705.04648},
  year   = {2017}
}

Comments

8 pages, 1 table