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.

Previous Showing 11-17 of 17 results.

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

A124439 Complete list of solutions to y^2 = x^3 + 17; sequence gives x values.

Original entry on oeis.org

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

Views

Author

Keywords

Comments

The solutions here are listed in the order given by Mordell. See A029728 for a better version (with comments and references).

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).

Crossrefs

Cf. A124451 (y values), A029728.

A124451 Complete list of solutions to y^2 = x^3 + 17; sequence gives y values.

Original entry on oeis.org

4, 3, 5, 9, 23, 282, 375, 378661
Offset: 1

Views

Author

Keywords

Comments

The solutions here are listed in the order given by Mordell. See A029728 and A029727 for a better version (with comments and references).

References

  • L. J. Mordell, Diophantine Equations, Ac. Press, p. 246.

Crossrefs

Cf. A124439 (x values). See A029728 for further comments and references.

A303615 Complete list of solutions to y^2 + y = x^3 - 525x + 10156; sequence gives x values.

Original entry on oeis.org

-29, -25, -20, -14, -5, 5, 14, 16, 20, 25, 49, 70, 79, 130, 250, 305, 400, 695, 1555, 1645, 18895
Offset: 1

Views

Author

Tomohiro Yamada, May 29 2018

Keywords

Comments

This equation gives the elliptic curve (W46) studied by Stroeker and de Weger. This curve has rank 3 with generators P1 = (25, 112), P2 = (-20, 112) and P3 = (70, 562). The list gives all integer points in this curve.
This equation can be transformed to A000332(n) = A000579(m) by x = (15/2)m^2 - (75/2)m + 25 and y = (225/2)n^2 - (675/2)n + 112. Hence, A000332(n) = A000579(m) (n >= 4, m >= 6) has no integer solutions other than (n, m)= (4, 6) and (10, 10).

Examples

			a(6) = 5: 5^3 - 525 * 5 + 10156 = 7656 = 88 * 87.
		

Crossrefs

Cf. A029728 (the complete list of solutions x to y^2=x^3+17), A102461 (the complete list of solutions n to A000217(n) = A027568(m)).

A309071 Complete list of solutions to y^2 = x^3 + 20*x; sequence gives x values.

Original entry on oeis.org

0, 4, 5, 720
Offset: 1

Views

Author

Seiichi Manyama, Jul 10 2019

Keywords

Comments

(x,y) = (0,0) is this solution. Consider x > 0. If x is square, x^2 + 20 is square and we get (x,y) = (4,12). If x is not square, x = i^2*j where j is squarefree. j | x^2 + 20, so j is 2,5 or 10. If j = 2 or 10, there is no such (x,y). If j = 5, (y/5)^2 = i^2*(5*i^4 + 4). So 5*i^4 + 4 = k^2. That is k^2 - 5*i^4 = 4. i^2 is a square Fibonacci number. i^2 = 1 or 144, so x = 5 or 720.

Examples

			  0^3 + 20*  0 =         0 =     0^2.
  4^3 + 20*  4 =       144 =    12^2.
  5^3 + 20*  5 =       225 =    15^2.
720^3 + 20*720 = 373262400 = 19320^2.
		

Crossrefs

Programs

  • PARI
    for(k=0, 1e5, if(issquare(k*(k^2+20)), print1(k", ")))
    
  • SageMath
    [i[0] for i in EllipticCurve([20, 0]).integral_points()] # Seiichi Manyama, Aug 25 2019

A316456 Complete list of solutions to y^2 = x^3 - 7x + 10; sequence gives x values.

Original entry on oeis.org

-3, -2, -1, 1, 2, 3, 5, 9, 13, 31, 41, 67, 302
Offset: 1

Views

Author

Tomohiro Yamada, Jul 04 2018

Keywords

Comments

Bremner and Tzanakis showed that the list of solutions is complete.
The elliptic curve given by this equation has rank 2 over the rationals with generators (1, 2) and (2, 2).
Since there exist two integer points (x, y) and (x, -y) for each x in the sequence (we can easily see that y <> 0 for such an x), this elliptic curve has exactly 26 integer points.

Crossrefs

Cf. A029728 (y^2 = x^3 + 17), A047694 (y^2 = C(x,0) + C(x,1) + C(x,2) + C(x,3))

Programs

  • SageMath
    EllipticCurve([0,0,0,-7,10]).integral_points()

A317053 Complete list of solutions to y^2 + y = x^3 - 525x + 10156 with y > 0; sequence gives positive y values.

Original entry on oeis.org

31, 74, 76, 87, 112, 121, 319, 562, 679, 1462, 3937, 5312, 7987, 18312, 61312, 66712, 2597287
Offset: 1

Views

Author

Tomohiro Yamada, Jul 20 2018

Keywords

Comments

This equation gives the elliptic curve (W46) studied by Stroeker and de Weger. This curve has rank 3 with generators P1 = (25, 112), P2 = (-20, 112) and P3 = (70, 562). The list gives all integer points with y > 0 in this curve.
Each positive y corresponds to a negative solution -y - 1, so that the sequence gives all y values of solutions.
Some y values corresponds to three solutions. For y = 87, we have x = -25, 5 or 20. For y = 112, we have x = -20, -5 or 25. Any other value of y corresponds to a unique solution.
This equation can be transformed to A000332(n) = A000579(m) by x = (15/2)m^2 - (75/2)m + 25 and y = (225/2)n^2 - (675/2)n + 112. Hence, A000332(n) = A000579(m) (n >= 4, m >= 6) has no integer solutions other than (n, m)= (4, 6) and (10, 10).

Examples

			a(1) = 31: (-29)^3 - 525 * (-29) + 10156 = 996 = 31 * 32.
		

Crossrefs

Cf. A303615 (x values)
Cf. A029728 (the complete list of solutions x to y^2 = x^3 + 17), A102461 (the complete list of solutions n to A000217(n) = A027568(m)).

Programs

  • SageMath
    EllipticCurve([0, 0, 1, -525, 10156]).integral_points()
Previous Showing 11-17 of 17 results.