English

Prime number conjectures from the Shapiro class structure

Number Theory 2020-03-03 v3

Abstract

The height H(n)H(n) of nn, introduced by Pillai in 1929, is the smallest positive integer ii such that the iith iterate of Euler's totient function at nn is 11. H. N. Shapiro (1943) studied the structure of the set of all numbers at a height. We state a formula for the height function due to Shapiro and use it to list steps to generate numbers at any height. This turns out to be a useful way to think of this construct. In particular, we extend some results of Shapiro regarding the largest odd numbers at a height. We present some theoretical and computational evidence to show that HH and its relatives are closely related to the important functions of number theory, namely π(n)\pi(n) and the nnth prime pnp_n. We conjecture formulas for π(n)\pi(n) and pnp_n in terms of the height function.

Cite

@article{arxiv.1903.09619,
  title  = {Prime number conjectures from the Shapiro class structure},
  author = {Hartosh Singh Bal and Gaurav Bhatnagar},
  journal= {arXiv preprint arXiv:1903.09619},
  year   = {2020}
}

Comments

23 Pages. Published version

R2 v1 2026-06-23T08:16:36.099Z