A086056 Decimal expansion of Pi/(2e).

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

Offset

0,1

References

Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Sections 1.4.3 and 7.2, pp. 22, 459.

Links

Table of n, a(n) for n=0..101.

Victor S. Adamchik, The Multiple Gamma Function and Its Application to Computation of Series, Ramanujan J. vol. 9, no 3. (2005) 271-288.

Christophe Chesneau, An original approximation involving Pi, the Euler-Mascheroni constant and the Catalan constant, hal-04692308, [math], 2024.

Christophe Chesneau, On Surprising Approximations Involving Multiple Mathematical Constants, Pan-Amer. J. Math. (2025) Vol. 4, No. 2. See p. 8.

Zdzislaw A. Melzak, Infinite products for πe and π/e, Amer. Math. Monthly 68 (1961) 39-41.

Eric Weisstein's World of Mathematics, Euler-Mascheroni Constant Approximations.

Eric Weisstein's World of Mathematics, InfiniteProduct.

Eric Weisstein's World of Mathematics, Masser-Gramain Constant.

Formula

Equals Integral_{x>=0} cos(x)/(x^2+1) dx = Integral_{x>=0} x*sin(x)/(x^2+1) dx. - Jean-François Alcover, Mar 28 2013

Equals Product_{k>=1} (1 + 2/k)^((-1)^(k+1) * k). - Amiram Eldar, Jul 16 2020

Example

0.57786367489546085895504659165634814956042551...

Maple

Digits:=100: evalf(Pi/(2*exp(1))); # Wesley Ivan Hurt, Jan 07 2017

Mathematica

First@ RealDigits@ N[Pi/(2 E), 120] (* Michael De Vlieger, Jan 07 2017 *)

Prog

(PARI) Pi/(2*exp(1)) \\ Michel Marcus, Jan 07 2017

Crossrefs

Cf. A216184 (Integral_{x>=0} sin(x)/(x^2+1)).

Sequence in context: A065773 A114916 A001989 * A154475 A375336 A264527

Adjacent sequences: A086053 A086054 A086055 * A086057 A086058 A086059

Keyword

nonn,cons,easy,changed

Author

Eric W. Weisstein, Jul 07 2003

Status

approved