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.

A194687 Least k such that the rank of the elliptic curve y^2 = x^3 - k^2*x is n, or -1 if no such k exists.

Original entry on oeis.org

1, 5, 34, 1254, 29274, 48272239, 6611719866
Offset: 0

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Author

Keywords

Comments

Fermat found a(0), Biling found a(1), and Wiman found a(2)-a(4). Rogers found upper bounds on a(5) and a(6) equal to their true value; Rathbun and an unknown author verified them as a(5) and a(6), respectively.
a(7) <= 797507543735, see Rogers 2004.

References

  • G. Billing, "Beiträge zur arithmetischen theorie der ebenen kubischen kurven geschlechteeins", Nova Acta Reg. Soc. Sc. Upsaliensis (4) 11 (1938), Nr. 1. Diss. 165 S.
  • N. Rogers, "Elliptic curves x^3 + y^2 = k with high rank", PhD Thesis in Mathematics, Harvard University (2004).
  • A. Wiman, "Über rationale Punkte auf Kurven y^2 = x(x^2-c^2)", Acta Math. 77 (1945), pp. 281-320.

Crossrefs

Programs

  • PARI
    r(n)=ellanalyticrank(ellinit([0,0,0,-n^2,0]))[1]
    rec=0;for(n=1,1e4,t=r(n);if(t>rec,rec=t;print("r("n") = "t)))

Extensions

Escape clause added to definition by N. J. A. Sloane, Jul 01 2024

A349511 a(n) = Sum_{k=n^2..3*n^2-3*n+1} binomial(n^3, k).

Original entry on oeis.org

1, 1, 162, 129426405, 16891063036609237658, 18250180714636047151855346313907038815, 1291091703201646062849529792547495285890126156377393082996087554, 15934719293558661243731879701489946881532638280926268234547722632676376681552065231576737967805230
Offset: 0

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Author

Stefano Spezia, Nov 20 2021

Keywords

Comments

a(n) is an upper bound of the number of vertices of the polytope of the n X n X n stochastic tensors, or equivalently, of the number of Latin squares of order n, or equivalently, of the number of n X n X n line-stochastic (0,1)-tensors (see Zhang et al.).

Crossrefs

Programs

  • Mathematica
    a[n_]:=Sum[Binomial[n^3,k],{k,n^2,3n^2-3n+1}]; Array[a,8,0]

Formula

A349508(n)/A349509(n) <= A319510(n) < a(n) < A349512(n) (see Corollary 7 in Zhang et al., 2021).
a(n) = binomial(n^3, n^2)*2F1([1, n^2-n^3], [1+n^2], -1) - binomial(n^3, 2-3*n+3*n^2)*2F1([1, 2-3*n+3*n^2-n^3], [3(1-n+n^2)], -1), where 2F1 is the hypergeometric function.
a(n) ~ exp(3*n^2 - 9*n/2 + 3) * n^(3*n*(n-1)) / (sqrt(2*Pi) * 3^(3*n^2 - 3*n + 3/2)). - Vaclav Kotesovec, Dec 05 2021

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

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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.

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

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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).
Showing 1-4 of 4 results.