Integer Subsets with High Volume and Low Perimeter

Abstract

We consider a certain variation of the 'isoperimetric problem' adopted for subsets of nonnegative integers. More specifically, we explore the sequence P(n) as described in OEIS A186053. We provide the first exact formulas for P(n) including multiple recursive relations involving auxiliary functions as well as concise and satisfying representations and even quasi-explicit formulas. We also discuss some of the intricate fractal-like symmetry of the sequence as well as the development of algorithms for computing P(n). We conclude with open questions for further research. Note this is a more developed, but more concise version of a previous arXiv paper arXiv:1107.2954 by the name "Sets with High Volume and Low Perimeter".