cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A356731 Conductor of the elliptic curve y^2 = x^3 - n.

Original entry on oeis.org

144, 1728, 972, 432, 10800, 15552, 5292, 576, 3888, 14400, 13068, 972, 73008, 84672, 24300, 432, 41616, 15552, 12996, 10800, 190512, 209088, 57132, 15552, 10800, 97344, 36, 1764, 363312, 388800, 103788, 1728, 470448, 499392, 44100, 3888, 197136, 623808, 164268, 43200, 726192
Offset: 1

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Author

Jianing Song, Aug 24 2022

Keywords

Comments

The discriminant of the elliptic curve y^2 = x^3 - n is -432*n^2 and the rank is A060951(n).
a(n*t^6) = a(n) for all t since the elliptic curve y^2 = x^3 - n*t^6 can be written as (y/t^3)^2 = (x/t^2)^3 - n, and the conductor is an invariant of elliptic curves.
Conjectures: (Start)
(i) a(27*n) = A356730(n) for all n.
(ii) a(n) is divisible by 36, and a(n) = 36 <=> n is 27 times a sixth power, a(n) = 108 <=> n is 108 times a sixth power, a(n) = 144 <=> n is a sixth power; moreover, it seems that a(n) is divisible by 36*n^2 if n is squarefree. (End)

Crossrefs

Programs

  • PARI
    a(n) = ellglobalred(ellinit([0,0,0,0,-n]))[1]

A385881 Algebraic rank of elliptic curve y^2 = x^3 - n*x - n.

Original entry on oeis.org

0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 2, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 2, 1, 1, 0, 0, 0, 0, 0, 1, 2, 1, 1, 2, 2, 0, 2, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 2, 0, 1, 0, 1, 1, 1, 0, 1, 2, 1
Offset: 1

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Author

Shreyansh Jaiswal, Aug 20 2025

Keywords

Comments

Terms from n = 43 onward are the analytic ranks (see PARI code) of the corresponding elliptic curves. By the BSD conjecture, these are expected to equal the algebraic ranks. Thus, the validity of these terms is conditional on BSD.

Examples

			a(1) = 0 because y^2 = x^3 - x - 1 has rank 0.
		

Crossrefs

Programs

  • PARI
    a(n) = ellanalyticrank( ellinit([0, 0, 0, -n, -n]) )[1]; \\ Michel Marcus, Aug 20 2025
  • SageMath
    for k in range(1, 43):
        E = EllipticCurve([-k, -k])
        print(E.rank(), end=", ")
    

Extensions

More terms from Michel Marcus, Aug 20 2025
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