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.
%I A086056 #55 Feb 16 2025 08:32:50
%S A086056 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,
%T A086056 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,
%U A086056 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
%N A086056 Decimal expansion of Pi/(2e).
%D A086056 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.
%H A086056 Victor S. Adamchik, <a href="http://dx.doi.org/10.1007/s11139-005-1868-3">The Multiple Gamma Function and Its Application to Computation of Series</a>, Ramanujan J. vol. 9, no 3. (2005) 271-288.
%H A086056 Christophe Chesneau, <a href="https://hal.science/hal-04692308">An original approximation involving Pi, the Euler-Mascheroni constant and the Catalan constant</a>, hal-04692308, [math], 2024.
%H A086056 Christophe Chesneau, <a href="https://doi.org/10.28919/cpr-pajm/4-2">On Surprising Approximations Involving Multiple Mathematical Constants</a>, Pan-Amer. J. Math. (2025) Vol. 4, No. 2. See p. 8.
%H A086056 Zdzislaw A. Melzak, <a href="http://www.jstor.org/stable/2311360">Infinite products for πe and π/e</a>, Amer. Math. Monthly 68 (1961) 39-41.
%H A086056 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Euler-MascheroniConstantApproximations.html">Euler-Mascheroni Constant Approximations</a>.
%H A086056 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/InfiniteProduct.html">InfiniteProduct</a>.
%H A086056 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Masser-GramainConstant.html">Masser-Gramain Constant</a>.
%F A086056 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
%F A086056 Equals Product_{k>=1} (1 + 2/k)^((-1)^(k+1) * k). - _Amiram Eldar_, Jul 16 2020
%e A086056 0.57786367489546085895504659165634814956042551...
%p A086056 Digits:=100: evalf(Pi/(2*exp(1))); # _Wesley Ivan Hurt_, Jan 07 2017
%t A086056 First@ RealDigits@ N[Pi/(2 E), 120] (* _Michael De Vlieger_, Jan 07 2017 *)
%o A086056 (PARI) Pi/(2*exp(1)) \\ _Michel Marcus_, Jan 07 2017
%Y A086056 Cf. A216184 (Integral_{x>=0} sin(x)/(x^2+1)).
%K A086056 nonn,cons,easy
%O A086056 0,1
%A A086056 _Eric W. Weisstein_, Jul 07 2003