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.

A091506 Decimal expansion of (2 + sqrt(2) + 5*arcsinh(1))/9.

Original entry on oeis.org

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

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Author

Eric W. Weisstein, Jan 16 2004

Keywords

Comments

Average distance between two points chosen at random on two different edges of a unit square.

Examples

			0.86900905527453446388497059434540662485671927963168056966035...
		

References

  • Jonathan Borwein, David Bailey, and Roland Girgensohn, Experimentation in Mathematics: Computational Paths to Discovery. Natick: A K Peters (2004): p. 66, Example 57(a).

Crossrefs

Cf. A091505.

Programs

  • Magma
    SetDefaultRealField(RealField(100)); (2 + Sqrt(2) + 5*Argsinh(1))/9; // G. C. Greubel, Aug 17 2018
  • Mathematica
    RealDigits[(2 + Sqrt[2] + 5ArcSinh[1])/9, 10, 120][[1]] (* Harvey P. Dale, May 22 2013 *)
  • PARI
    (2 + sqrt(2) + 5*asinh(1))/9 \\ G. C. Greubel, Aug 17 2018
    

Formula

Also equals (2 + sqrt(2) + 5*log(1 + sqrt(2)))/9. - Jean-François Alcover, Feb 14 2014
James D. Klein proved that this constant is equal to 2/3*int(int(sqrt(x^2 + y^2), x = 0..1), y = 0..1) + 1/3*int(int(sqrt(1 + (y - u)^2), u = 0..1), y = 0..1). - John M. Campbell, Apr 02 2016

Extensions

Broken link fixed by John M. Campbell, Apr 02 2016