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 A019610 #42 Sep 08 2022 08:44:44
%S A019610 4,2,6,9,8,6,7,1,1,1,3,3,6,7,8,3,5,3,2,7,3,1,7,7,5,4,3,4,7,7,3,2,8,7,
%T A019610 2,4,7,5,1,7,4,4,4,2,6,7,8,8,2,5,5,7,4,8,0,9,3,9,8,0,0,5,6,5,0,8,9,6,
%U A019610 1,4,3,0,5,5,7,8,6,6,5,4,0,3,7,8,6,2,8,1,9,3,4,8,5,5,2,3,6,9,7
%N A019610 Decimal expansion of Pi*e/2.
%D A019610 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.15 Glaisher-Kinkelin constant, p. 136.
%H A019610 Ivan Panchenko, <a href="/A019610/b019610.txt">Table of n, a(n) for n = 1..1000</a>
%H A019610 Z. 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.
%F A019610 Melzak's formula: lim_{n->infinity} Product_{k=1..2n+1} (1+2/k)^(k*(-1)^(k+1)) = Pi*e/2. - _Jean-François Alcover_, Apr 25 2014
%e A019610 4.26986711133678353273177543477328724751744426788255748...
%p A019610 Digits:=100: evalf(Pi*exp(1)/2); # _Wesley Ivan Hurt_, Aug 09 2014
%t A019610 RealDigits[(Pi*E)/2,10,120][[1]] (* _Harvey P. Dale_, Apr 16 2014 *)
%o A019610 (PARI) { default(realprecision, 100); x=(1/2)*Pi*exp(1); for(n=1, 100, d=floor(x); x=(x-d)*10; print1(d, ", ")) } \\ _Altug Alkan_, Nov 13 2015
%o A019610 (Magma) SetDefaultRealField(RealField(100)); R:= RealField(); Pi(R)*Exp(1)/2; // _G. C. Greubel_, Aug 24 2018
%Y A019610 Cf. A019609, A241420, A241421.
%K A019610 nonn,cons
%O A019610 1,1
%A A019610 _N. J. A. Sloane_