English

Elliptic Fermat numbers and elliptic divisibility sequence

Number Theory 2018-08-14 v1

Abstract

For a pair (E,P)(E,P) of an elliptic curve E/QE/\mathbb{Q} and a nontorsion point PE(Q)P\in E(\mathbb{Q}), the sequence of \emph{elliptic Fermat numbers} is defined by taking quotients of terms in the corresponding elliptic divisibility sequence (Dn)nN(D_{n})_{n\in\mathbb{N}} with index powers of two, i.e. D1D_{1}, D2/D1D_{2}/D_{1}, D4/D2D_{4}/D_{2}, etc. Elliptic Fermat numbers share many properties with the classical Fermat numbers, Fk=22k+1F_{k}=2^{2^k}+1. In the present paper, we show that for magnified elliptic Fermat sequences, only finitely many terms are prime. We also define \emph{generalized elliptic Fermat numbers} by taking quotients of terms in elliptic divisibility sequences that correspond to powers of any integer mm, and show that many of the classical Fermat properties, including coprimality, order universality and compositeness, still hold.

Keywords

Cite

@article{arxiv.1808.03846,
  title  = {Elliptic Fermat numbers and elliptic divisibility sequence},
  author = {Seoyoung Kim and Alexandra Walsh},
  journal= {arXiv preprint arXiv:1808.03846},
  year   = {2018}
}
R2 v1 2026-06-23T03:30:58.385Z