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 11-13 of 13 results.

A254980 Decimal expansion of the mean reciprocal Euclidean distance from a point in a unit 4D cube to a given vertex of the cube (named B_4(-1) in Bailey's paper).

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Feb 11 2015

Keywords

Examples

			0.96741202124116589866183643817815839013593700929996...
		

Crossrefs

Programs

  • Mathematica
    Ti2[x_] := (I/2)*(PolyLog[2, -I*x] - PolyLog[2, I*x]); B4[-1] = 2*Log[3] - (2/3) * Catalan + 2*Ti2[3 - 2*Sqrt[2]] - Sqrt[8]*ArcTan[1/Sqrt[8]] // Re; RealDigits[ B4[-1], 10, 104] // First
  • Python
    from mpmath import *
    mp.dps=105
    x=3 - 2*sqrt(2)
    Ti2x=(j/2)*(polylog(2, -j*x) - polylog(2, j*x))
    C = 2*log(3) - (2/3)*catalan + 2*Ti2x - sqrt(8) * atan(1/sqrt(8))
    print([int(n) for n in list(str(C.real)[2:-1])]) # Indranil Ghosh, Jul 03 2017

Formula

B_4(-1) = 2*log(3) - (2/3)*Catalan + 2*Ti_2(3-2*sqrt(2)) - sqrt(8) * arctan( 1/sqrt(8) ), where Ti_2(x) = (i/2)*(polylog(2, -i*x) - polylog(2, i*x)) (Ti_2 is the inverse tangent integral function).

Extensions

Name corrected by Amiram Eldar, Jun 04 2023

A263151 Decimal expansion of the ratio of the length of the latus rectum arc of any parabola to its focal length: sqrt(8) + log(3 + sqrt(8)).

Original entry on oeis.org

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

Views

Author

Martin Janecke, Oct 11 2015

Keywords

Comments

Twice the universal parabolic constant A103710.

Examples

			4.591174298785276148068596098378980775195664407277166967859950693...
		

Crossrefs

Equals twice A103710. Equals A010466 + A244920.

Programs

  • Mathematica
    First@ RealDigits[N[# + Log[3 + #] &@ Sqrt@ 8, 102]] (* Michael De Vlieger, Oct 11 2015 *)
  • PARI
    sqrt(8) + log(3 + sqrt(8)) \\ Michel Marcus, Oct 11 2015

A348669 Decimal expansion of 2*sqrt(2)*log(1 + sqrt(2))/(3*Pi).

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Oct 29 2021

Keywords

Comments

The average length of a random line segment in a unit square defined as follows. A line that is making a random angle with a given edge of the square is chosen, and a random distance of this line from a given vertex of this edge is chosen uniformly between 0 and the distance to the opposite vertex in the square. The segment is then being chosen by picking at random two points between the two intersection points of the line with the perimeter of the square.

Examples

			0.26450500700786984551577520129722526936340009096805...
		

Crossrefs

Programs

  • Maple
    evalf(sqrt(8/9)*arcsinh(1)/Pi, 120);  # Alois P. Heinz, Oct 29 2021
  • Mathematica
    RealDigits[2*Sqrt[2]*Log[1 + Sqrt[2]]/(3*Pi), 10, 100][[1]]
  • PARI
    2*sqrt(2)*log(1 + sqrt(2))/(3*Pi) \\ Michel Marcus, Oct 29 2021
Previous Showing 11-13 of 13 results.