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 1-4 of 4 results.

A175316 Decimal expansion of coth(Pi).

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Apr 01 2010

Keywords

Examples

			1.003741873197321288201552691194800017462452422...
		

Crossrefs

Programs

  • Maple
    Tau := 2*Pi: Digits := 120: (exp(Tau) + 1)/(exp(Tau) - 1):
    evalf(%)*10^110: ListTools:-Reverse(convert(floor(%), base, 10)); # Peter Luschny, May 21 2021
  • Mathematica
    RealDigits[Coth[Pi], 10, 110][[1]] (* Georg Fischer, Apr 03 2020 *)

Formula

Equals A175314 divided by A175315.
Equals (exp(tau) + 1)/(exp(tau) - 1), where tau = 2*Pi = A019692. - Peter Luschny, May 22 2021
From Wolfe Padawer, Jan 28 2023: (Start)
Equals Sum_{k>=-oo} 1/(Pi + Pi*k^2).
Equals 1 + Sum_{k>=0} 2*e^(-2*Pi*k - 2*Pi).
Equals 1 + lim_{n->oo} (2*e^(-2*Pi*n))*(e^(2*Pi*n) - 1)/(e^(2*Pi) - 1). (End)
Equals 1/A344505. - Hugo Pfoertner, Jun 24 2025

Extensions

a(42) ff. corrected by Georg Fischer, Apr 03 2020

A372822 a(n) = floor(n*tanh(Pi/2)).

Original entry on oeis.org

0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 55, 56, 57, 58, 59, 60, 61, 62, 63
Offset: 0

Views

Author

Paolo Xausa, Jul 04 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Floor[Range[0, 100]*Tanh[Pi/2]]

A096613 Values of k such that floor(k*tanh(Pi)) = floor((k+1) tanh(Pi)).

Original entry on oeis.org

268, 536, 804, 1072, 1341, 1609, 1877, 2145, 2414, 2682, 2950, 3218, 3487, 3755, 4023, 4291, 4560, 4828, 5096, 5364, 5633, 5901, 6169, 6437, 6706, 6974, 7242, 7510, 7779, 8047, 8315, 8583, 8852, 9120, 9388, 9656, 9925, 10193, 10461, 10729
Offset: 1

Views

Author

Eric W. Weisstein, Jun 30 2004

Keywords

Examples

			Floor(k*tanh(Pi)) = k-1 for 1<=k<=267, but floor(268*tanh(Pi)) = floor(269*tanh(Pi)) = 267, so 268 is the first member of the sequence.
		

Crossrefs

Cf. A344505.

Programs

  • Mathematica
    Select[Range[10^4], Floor[#*Tanh[Pi]] == Floor[(# + 1)*Tanh[Pi]] &] (* Amiram Eldar, Apr 14 2022 *)
    With[{c=Tanh[Pi]},SequencePosition[Table[Floor[c* n],{n,11000}],{x_,x_}][[;;,1]]] (* Harvey P. Dale, Aug 29 2025 *)

A347058 Decimal expansion of (1 + tanh(Pi)) / 2.

Original entry on oeis.org

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

Views

Author

Sean A. Irvine, Aug 14 2021

Keywords

Examples

			0.99813603811037497213234529000626835594844959540...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[(1 + Tanh[Pi])/2, 10, 120][[1]] (* Amiram Eldar, Jun 07 2023 *)

Formula

Equals exp(2*Pi) / (1 + exp(2*Pi)).
Equals Sum_{k>=0} (-1)^k * exp(-2*Pi*k).
Showing 1-4 of 4 results.