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.

A343851 Decimal expansion of the solution to the Heilbronn triangle problem for seven points in a unit square.

Original entry on oeis.org

0, 8, 3, 8, 5, 9, 0, 0, 9, 0, 0, 7, 5, 1, 3, 4, 0, 6, 6, 3, 7, 9, 6, 6, 7, 4, 3, 5, 4, 4, 7, 6, 0, 5, 5, 6, 8, 4, 4, 3, 2, 4, 7, 6, 8, 1, 9, 1, 6, 1, 4, 9, 8, 5, 2, 6, 1, 2, 3, 0, 0, 8, 8, 5, 6, 6, 2, 4, 3, 5, 0, 9, 5, 3, 5, 7, 5, 2, 4, 4, 8, 3, 9, 7, 6, 5, 5, 8, 6, 0, 3, 9, 8, 9, 6, 0, 8, 5, 3, 7, 1, 2
Offset: 0

Views

Author

Jeremy Tan, May 03 2021

Keywords

Comments

The Heilbronn triangle problem: find an arrangement of n points in a convex region such that the minimum area among triangles formed by three of the points is maximized.
The seven-point configuration in the square was found by Comellas and Yebra and proved optimal by Chen and Zeng.

Examples

			0.08385900900751340663796674354476...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 8.16, p. 527.

Crossrefs

Cf. A248866 (discrete Heilbronn triangle problem).

Programs

  • Mathematica
    First@ RealDigits@ N[Root[152x^3+12x^2-14x+1, x, 2], 105]
  • PARI
    polrootsreal(152*x^3+12*x^2-14*x+1)[2]

Formula

This is the smallest positive root of 152x^3 + 12x^2 - 14x + 1.

A379533 Decimal expansion of (sqrt(13) - 1)/36.

Original entry on oeis.org

0, 7, 2, 3, 7, 6, 4, 2, 4, 3, 1, 8, 4, 4, 4, 1, 4, 7, 0, 3, 1, 0, 8, 9, 4, 7, 9, 6, 5, 1, 9, 5, 8, 2, 2, 0, 7, 2, 9, 2, 0, 2, 6, 8, 2, 6, 0, 6, 8, 1, 2, 3, 9, 4, 7, 9, 7, 5, 1, 2, 5, 8, 4, 8, 9, 5, 1, 9, 9, 0, 8, 1, 8, 9, 7, 0, 2, 8, 0, 6, 7, 9, 2, 2, 3, 5, 0, 5, 3, 0, 0, 5, 6, 0, 6, 9, 1, 8, 6, 6, 0
Offset: 0

Views

Author

Stefano Spezia, Dec 24 2024

Keywords

Comments

Lower bound to the 8th Heilbronn triangle constant.

Examples

			0.072376424318444147031089479651958220729202682606812...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 8.16, p. 527.

Crossrefs

Programs

  • Mathematica
    RealDigits[(Sqrt[13]-1)/36,10,100][[1]]

Formula

Minimal polynomial: 108*x^2 + 6*x - 1. - Stefano Spezia, Aug 03 2025

A379534 Decimal expansion of (9*sqrt(65) - 55)/320.

Original entry on oeis.org

0, 5, 4, 8, 7, 5, 9, 9, 9, 1, 7, 0, 8, 9, 6, 7, 0, 8, 9, 7, 2, 8, 1, 0, 9, 9, 7, 1, 0, 2, 2, 9, 3, 5, 6, 3, 0, 6, 3, 1, 5, 4, 8, 9, 6, 0, 9, 5, 2, 4, 1, 1, 2, 6, 5, 3, 5, 7, 1, 6, 6, 6, 0, 9, 4, 8, 0, 4, 6, 4, 8, 2, 9, 9, 7, 5, 9, 7, 4, 8, 0, 7, 0, 8, 2, 5, 4, 3, 3, 8, 7, 5, 1, 4, 2, 2, 1, 1, 1, 8, 5
Offset: 0

Views

Author

Stefano Spezia, Dec 24 2024

Keywords

Comments

Lower bound to the 9th Heilbronn triangle constant.

Examples

			0.054875999170896708972810997102293563063154896095241...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 8.16, p. 527.

Crossrefs

Programs

  • Mathematica
    RealDigits[(9Sqrt[65]-55)/320,10,100][[1]]

Formula

Minimal polynomial: 320*x^2 + 110*x - 7. - Stefano Spezia, Aug 03 2025
Showing 1-3 of 3 results.