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.

Showing 1-7 of 7 results.

A319510 Rank of elliptic curve y^2 = x^3 - n^2 * x.

Original entry on oeis.org

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

Views

Author

Seiichi Manyama, Sep 24 2018

Keywords

Crossrefs

Programs

  • PARI
    {a(n) = ellanalyticrank(ellinit([0, 0, 0, -n^2, 0]))[1]}

Formula

a(n) = A060952(n^2).
a(A003273(n)) > 0.
a(A194687(n)) = n.
Empirical: a(n) = a(4*n). - Jose Aranda, Jul 02 2024

A309028 Smallest k>0 such that the elliptic curve y^2 = x^3 + k*x has rank n, if k exists.

Original entry on oeis.org

1, 3, 14, 323, 1918, 195843
Offset: 0

Views

Author

Seiichi Manyama, Jul 08 2019

Keywords

Comments

See A309029 for the smallest negative k.

Crossrefs

Extensions

a(5) from Vaclav Kotesovec, Jul 14 2019

A309060 Least k such that the rank of the elliptic curve y^2 = x^3 + k^2*x is n.

Original entry on oeis.org

1, 3, 17, 627, 14637
Offset: 0

Views

Author

Seiichi Manyama, Jul 09 2019

Keywords

Comments

From Jose Aranda, Jun 30 2024: (Start)
A319510(n even) = A309061(n/2), A319510(n odd) = A309061(2*n) (Empirical).
A194687(5) = 48272239 which implies a(5) <= 96544478 (Checked).
A194687(6) = 6611719866 which implies a(6) <= 3305859933 (Checked).
A194687(7) <= 797507543735 which implies a(7) <= 1595015087470 (Checked). (End)

Examples

			A309061(1) = 0.
A309061(3) = 1.
A309061(17) = 2.
		

Crossrefs

Programs

  • PARI
    {a(n) = my(k=1); while(ellanalyticrank(ellinit([0, 0, 0, k^2, 0]))[1]<>n, k++); k}

Formula

A309061(a(n)) = n.

A309029 Smallest k>0 such that the elliptic curve y^2 = x^3 - k*x has rank n, if k exists.

Original entry on oeis.org

1, 2, 17, 82, 5037, 49042
Offset: 0

Views

Author

Seiichi Manyama, Jul 08 2019

Keywords

Comments

See A309028 for the smallest positive k.

Crossrefs

Extensions

a(5) from Vaclav Kotesovec, Jul 09 2019

A309068 Least k such that the rank of the elliptic curve y^2 = x^3 - k^2 is n.

Original entry on oeis.org

1, 2, 11, 362, 7954
Offset: 0

Views

Author

Seiichi Manyama, Jul 10 2019

Keywords

Crossrefs

Programs

  • PARI
    {a(n) = my(k=1); while(ellanalyticrank(ellinit([0, 0, 0, 0, -k^2]))[1]<>n, k++); k}

A372543 Least k such that the rank of the elliptic curve y^2 = x^3 - k^2*x + 1 is n, or -1 if no such k exists.

Original entry on oeis.org

0, 1, 2, 4, 8, 17, 61, 347, 3778, 11416
Offset: 0

Views

Author

Jose Aranda, Jul 04 2024

Keywords

Comments

This family of curves quickly reaches a moderate value of rank with a relatively small parameter k.
By heuristic search (see links), a(10) <= 216493 and a(11) <= 1448203.

Crossrefs

Programs

  • PARI
    a(n,startAt=0)=for(k=startAt, oo, my(t=ellrank(ellinit([-k^2, +1]))); if(t[2]n, warning("k=",k," has rank in ",t[1..2]); next); if(t[1]n, error("Cannot determine if a(",n,") is ",k," or larger; rank is in ",t[1..2])); return(k)) \\ Charles R Greathouse IV, Jul 08 2024
    
  • PARI
    \\ See Aranda link.

A374926 Least k such that the rank of the elliptic curve y^2 = x^3 - x + k^2 is n, or -1 if no such k exists.

Original entry on oeis.org

1, 2, 5, 24, 113, 337, 6310, 78560, 423515, 765617
Offset: 1

Views

Author

Jose Aranda, Jul 24 2024

Keywords

Comments

This family of curves quickly reaches a moderate value of rank with a relatively low "k" parameter. And is fully analyzed in Tadik's work (see link). Tadik finds 11 terms, a rank lower bound and shows the torsion group is always trivial. The evolution of the rank is shown in detail, finding that a(11) <= 1118245045.
I have sequentially checked the first 10 terms, thus proving that they are the least k for each rank.

Examples

			The curve C[1] = [-1,1^2] has rank one, with generator [1,-1].The rank of C[2] = [-1,2^2] is 2 because it has two generators:PARI> e=ellinit([-1,2^2] );ellgenerators(e) = [[-1, 2], [0, 2]].If k>1, the curve C[k] always has at least two generators: [0,k], [-1,k], then its minimum rank is two.
		

Crossrefs

Showing 1-7 of 7 results.