A175316 Decimal expansion of coth(Pi).
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
Examples
1.003741873197321288201552691194800017462452422...
Links
- Michael I. Shamos, A catalog of the real numbers, (2007). See p. 28.
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 (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