Let $S$ be a finite set of primes. An elliptic curve $E/\mathbb{Q}$ is said to have good reduction outside $S$ if its minimal discriminant (equivalently, its conductor) is only divisible by primes in $S$. This table lists the numbers of elliptic curves $E/\mathbb{Q}$ with good reduction outside $S$ counted in two different ways: up to $\mathbb{Q}$-isomorphism, and up to $\overline{\mathbb{Q}}$-isomorphism.
Parameters
$S$
— set of primes
Comments
(1)
Elliptic curves over $\mathbb{Q}$ with good reduction outside of the first $n$ have been computed by several authors: $n=0$ by Tate (see [6]), $n=1$ by Ogg [6], $n=2$ by Coghlan [3] and Stephens [7], $n=3,4,5$ by von Känel and Matschke [4] and Bennett, Gherga and Rechnitzer [1], $n=6$ heuristically by Best and Matschke [2], $n=7,8,9^*$ by Matschke [9] ($n=9$ assumes GRH).
References
[1]
Michael A. Bennett, Adela Gherga, and Andrew Rechnitzer, "Computing elliptic curves over Q". Math. Comp., 88(317):1341–1390, 2019.
[2]
A. Best, B. Matschke, "Elliptic curves with good reduction outside of the first six primes". 2020 (arXiv) (github)
[3]
Francis Coghlan, "Elliptic Curves with Conductor $2^m 3^n$". Ph.D. thesis, Manchester, England, 1967.
[4]
R. von Känel, B. Matschke, "Solving S-unit, Mordell, Thue, Thue-Mahler and generalized Ramanujan-Nagell equations via Shimura-Taniyama conjecture". 2016 (arXiv) (github)
[5]
Angelos Koutsianas, "Computing all elliptic curves over an arbitrary number field with prescribed primes of bad reduction". Exp. Math., 28(1):1–15, 2019. (arXiv) (github)
[6]
Andrew P. Ogg, "Abelian curves of 2-power conductor". Math. Proc. Camb. Philos. Soc., 62(2):143–148, 1966.
[7]
Nelson M. Stephens, "The Birch Swinnerton-Dyer Conjecture for Selmer curves of positive rank". Ph.D. Thesis, Manchester, 1965.
Computed in interval or ball arithmetic throughout, so the digits written follow from the width of the result rather than from a guard chosen in advance.