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 1-8 of 8 results.

A029728 Complete list of solutions to y^2 = x^3 + 17; sequence gives x values.

Original entry on oeis.org

-2, -1, 2, 4, 8, 43, 52, 5234
Offset: 1

Views

Author

Keywords

Comments

Comments by Henri Cohen on the proof that the list of solutions is complete: (Start)
This is now completely standard. Cremona's mwrank program tells us that this is an elliptic curve of rank 2 with generators P1=(-2,3) and P2=(4,9).
We now apply the algorithm (essentially due to Tzanakis and de Weger) described in Nigel Smart's book on the algorithmic solution of Diophantine equations: using Sinnou David's bounds on linear forms in elliptic logarithms one finds that if P is an integral point then P=aP1+bP2 for |a| and |b| less than a huge bound B (typically 10^100, sometimes more, I didn't do the computation here), but the main point is that B is completely explicit. One then uses the LLL algorithm: this is crucial.
A first application reduces the bound to 200, say, then a second application to 20 and sometimes a third to 12 (at this point it is not necessary). Then a very small search gives all the possible integer points. (End)

References

  • L. J. Mordell, Diophantine Equations, Ac. Press, p. 246.
  • T. Nagell, Einige Gleichungen von der Form ay^2+by+c=dx^3, Vid. Akad. Skrifter Oslo, Nr. 7 (1930).
  • Silverman, Joseph H. and John Tate, Rational Points on Elliptic Curves. New York: Springer-Verlag, 1992.

Crossrefs

Cf. A029727 (y values).
x values of solutions to y^2 = x^3 + a*x + b;
A134107 (a= 0, b=-207),
A134074 (a= 0, b= 73),
A134042 (a= 0, b= 113),
A134103 (a= 0, b= 225),
A134105 (a= 0, b= 297),
A134167 (a= 0, b=1025),
A316456 (a=-7, b= 10),
A309071 (a=20, b= 0).

Programs

  • Magma
    Sort([ p[1] : p in IntegralPoints(EllipticCurve([0,17])) ]); // Sergei Haller (sergei(AT)sergei-haller.de), Dec 21 2006
    
  • Mathematica
    ok[x_] := Reduce[y>0 && y^2 == x^3 + 17, y, Integers] =!= False; Select[Table[x, {x, -2, 10000}], ok ] (* Jean-François Alcover, Sep 07 2011 *)
  • SageMath
    [i[0] for i in EllipticCurve([0, 17]).integral_points()] # Seiichi Manyama, Aug 25 2019

A134043 Complete list of solutions to y^2 = x^3 + 113; sequence gives y values.

Original entry on oeis.org

7, 11, 25, 38, 133, 8669
Offset: 1

Views

Author

Artur Jasinski, Oct 03 2007

Keywords

Comments

For corresponding x values see A134043.

Examples

			a(1)^2 = 7^2 = 49 = A134042(1)^3 + 113 = -64 + 113.
a(2)^2 = 11^2 = 121 = A134042(2)^3 + 113 = 8 + 113.
a(3)^2 = 25^2 = 625 = A134042(3)^3 + 113 = 512 + 113.
a(4)^2 = 38^2 = 1444 = A134042(4)^3 + 113 = 1331+ 113.
a(5)^2 = 133^2 = 17689 = A134042(5)^3 + 113 = 17576 + 113.
a(6)^2 = 8669^2 = 75151561 = A134042(6)^3 + 113 = 75151448 + 113.
		

Crossrefs

Programs

  • Magma
    Sort([ Abs(p[2]) : p in IntegralPoints(EllipticCurve([0, 113])) ]); /* adapted from A029727 */
  • Mathematica
    (Program does not produce first two terms) a = {}; Do[k = n^2 - (Floor[n^(2/3)])^3; If[(k > 112) && (k < 113), AppendTo[a, n]], {n, 1, 100000}]; a

Extensions

Edited and corrected by Klaus Brockhaus, Oct 04 2007

A134105 Complete list of solutions to y^2 = x^3 + 297; sequence gives x values.

Original entry on oeis.org

-6, -2, 3, 4, 12, 34, 48, 1362, 93844
Offset: 1

Views

Author

Klaus Brockhaus, Oct 08 2007

Keywords

Comments

For corresponding y values and examples see A134104.
The parameter -297 of the curve corresponds to A200218(1). a(9)=A200216(1). - Artur Jasinski, Nov 29 2011

Crossrefs

Programs

  • Magma
    Sort([ p[1] : p in IntegralPoints(EllipticCurve([0, 297])) ]); /* adapted from A029728 */
    
  • Mathematica
    sol[x_] := Solve[y > 0 && x^3 - y^2 == -297, y, Integers];
    Reap[For[x = 1, x < 10^5, x++, sx = sol[x]; If[sx != {}, xy = {x, y} /. sx[[1]]; Print[xy]; Sow[xy]]; sx = sol[-x]; If[sx != {}, xy = {-x, y} /. sx[[1]]; Print[xy]; Sow[xy]]]][[2, 1]][[All, 1]] // Sort (* Jean-François Alcover, Feb 07 2020 *)
  • SageMath
    [i[0] for i in EllipticCurve([0, 297]).integral_points()] # Seiichi Manyama, Aug 26 2019

A134107 Complete list of solutions to y^2 = x^3 - 207; sequence gives x values.

Original entry on oeis.org

6, 12, 18, 31, 312, 331, 367806
Offset: 1

Views

Author

Klaus Brockhaus, Oct 08 2007

Keywords

Comments

For corresponding y values and examples see A134106.

Crossrefs

Programs

  • Magma
    Sort([ p[1] : p in IntegralPoints(EllipticCurve([0, -207])) ]); /* adapted from A029728 */
    
  • SageMath
    [i[0] for i in EllipticCurve([0, -207]).integral_points()] # Seiichi Manyama, Aug 25 2019

A080761 Positive numbers of the form y^2 - x^3, x and y >= 1.

Original entry on oeis.org

1, 3, 8, 9, 12, 15, 17, 18, 19, 22, 24, 28, 30, 35, 36, 37, 38, 40, 41, 44, 48, 54, 55, 56, 57, 63, 64, 65, 68, 71, 73, 79, 80, 89, 92, 94, 97, 98, 99, 100, 101, 105, 106, 107, 108, 112, 113, 117, 119, 120, 121, 128, 129, 131, 132, 136, 138, 141, 142, 143, 145, 148, 151
Offset: 1

Views

Author

Cino Hilliard, Mar 10 2003

Keywords

Comments

From Artur Jasinski, Oct 03 2007: (Start)
Some numbers have multiple partitions:
8 = 4^2 - 8^3 = 312^2 - 46^3,
9 = 6^2 - 3^3 = 15^2 - 6 ^3 = 253^2 - 40^3. (End)
This is Mordell's equation with the condition that x and y are positive. Sequence A054504 lists the n for which there is no solution to Mordell's equation. Hence, none of those numbers will be in this sequence. The terms of this sequence can be determined by looking at the link to Gebel's data. - T. D. Noe, Mar 23 2011

Examples

			8 is in the sequence since 3^2 = 1^3 + 8.
		

Crossrefs

Complement of A080762.
Cf. sequences for n^3+7, n^3+17, n^3+3, n^3+2, n^3+5.

Programs

  • Mathematica
    With[{nn=100},Take[Union[Select[First[#]^2-Last[#]^3&/@Tuples[Range[ 20nn],2],#>0&]],nn]] (* Harvey P. Dale, Jul 10 2012 *)
  • PARI
    diop(n,m) = { for(p=1,m, for(x=1,n, y=x*x*x+p; if(issquare(y),print1(p" "); break) ) ) }

Extensions

"Positive" added to definition by N. J. A. Sloane, Oct 06 2007

A134074 Complete list of solutions to y^2 = x^3 + 73; sequence gives x values.

Original entry on oeis.org

-4, 2, 3, 6, 72, 356
Offset: 1

Views

Author

Klaus Brockhaus, Oct 07 2007

Keywords

Comments

For corresponding y values and examples see A134073.

Crossrefs

Programs

  • Magma
    Sort([ p[1] : p in IntegralPoints(EllipticCurve([0, 73])) ]); /* adapted from A029728 */
    
  • SageMath
    [i[0] for i in EllipticCurve([0, 73]).integral_points()] # Seiichi Manyama, Aug 25 2019

A134103 Complete list of solutions to y^2 = x^3 + 225; sequence gives x values.

Original entry on oeis.org

-6, -5, 0, 4, 6, 10, 15, 30, 60, 180, 336, 351, 720114
Offset: 1

Views

Author

Klaus Brockhaus, Oct 08 2007

Keywords

Comments

For corresponding y values and examples see A134102.

Crossrefs

Programs

  • Magma
    { x: x in Sort([ p[1] : p in IntegralPoints(EllipticCurve([0, 225])) ]) }; /* adapted from A029728 */
    
  • SageMath
    [i[0] for i in EllipticCurve([0, 225]).integral_points()] # Seiichi Manyama, Aug 26 2019

A134167 Complete list of solutions to y^2 = x^3 + 1025; sequence gives x values.

Original entry on oeis.org

-10, -5, -4, -1, 4, 10, 20, 40, 50, 64, 155, 166, 446, 920, 3631, 3730
Offset: 1

Views

Author

Klaus Brockhaus, Oct 11 2007

Keywords

Comments

For corresponding y values and examples see A134166.

Crossrefs

Programs

  • Magma
    { x: x in Sort([ p[1] : p in IntegralPoints(EllipticCurve([0, 1025])) ]) }; /* adapted from A029728 */
    
  • SageMath
    [i[0] for i in EllipticCurve([0, 1025]).integral_points()] # Seiichi Manyama, Aug 26 2019
Showing 1-8 of 8 results.