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 1-4 of 4 results.

A309069 Least k such that the rank of the elliptic curve y^2 = x^3 + k^2 is n.

Original entry on oeis.org

1, 3, 15, 427, 17353
Offset: 0

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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}

A309061 Rank of elliptic curve y^2 = x^3 + n^2 * x.

Original entry on oeis.org

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

Views

Author

Seiichi Manyama, Jul 09 2019

Keywords

Crossrefs

Programs

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

Formula

a(n) = A060953(n^2).

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 1-4 of 4 results.