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 1-3 of 3 results.

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 1-3 of 3 results.