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 A212879 #25 Oct 25 2024 06:28:25
%S A212879 5,2,1,5,6,4,0,4,6,8,6,4,9,3,9,8,4,1,1,5,8,1,8,0,2,6,9,6,2,8,1,9,0,0,
%T A212879 5,3,8,5,6,4,0,5,6,7,8,2,7,7,8,9,5,6,3,1,9,2,5,5,6,8,1,2,2,4,4,4,2,4,
%U A212879 8,6,9,5,2,3,6,2,2,8,0,8,1,6,5,4,1,1,2,7,4,9,3,6,6,7,5,2,4,1,0,9,6,6,5,3,7
%N A212879 Decimal expansion of the absolute value of i!.
%C A212879 Also absolute value of Gamma(i).
%H A212879 G. C. Greubel, <a href="/A212879/b212879.txt">Table of n, a(n) for n = 0..5000</a>
%F A212879 Equals abs(Gamma(i)), since i! = Gamma(1+i) = i*Gamma(i).
%F A212879 Equals sqrt(Pi/sinh(Pi)). - _Vaclav Kotesovec_, Dec 10 2015
%F A212879 Equals Product_{k>=1} k/sqrt(k^2+1) = sqrt(A090986). - _Amiram Eldar_, Oct 25 2024
%e A212879 0.5215640468649398411581802696...
%t A212879 N[Sqrt[Pi/Sinh[Pi]], 103] (* _Vaclav Kotesovec_, Dec 10 2015 *)
%t A212879 RealDigits[Abs[I!], 10, 120][[1]] (* _Amiram Eldar_, Oct 25 2024 *)
%o A212879 (PARI) abs(gamma(I))
%Y A212879 Cf. A090986, A212877 (real(i!)), A212878 (-imag(i!)), A212880 (-arg(i!)).
%K A212879 nonn,cons,easy
%O A212879 0,1
%A A212879 _Stanislav Sykora_, May 29 2012