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 A341233 #15 Feb 08 2021 11:47:10
%S A341233 1,1,12,96,320,3840,161280,516096,46448640,185794560,2270822400,
%T A341233 163499212800,1821848371200,51011754393600,10712468422656000,
%U A341233 9794256843571200,555007887802368000,139861987726196736000,1449478781889675264000,49059281848573624320000
%N A341233 Denominator of the expected fraction of guests without a napkin in Conway's napkin problem with n guests.
%F A341233 A341232(n)/a(n) = Sum_{k=2..n} (1-2^(2-k))/k!.
%F A341233 Lim_{n->oo} A341232(n)/a(n) = (2-sqrt(e))^2 (A248788).
%e A341233 0, 0, 1/12, 11/96, 39/320, 473/3840, 19897/161280, 63683/516096, 5731597/46448640
%o A341233 (Python)
%o A341233 from sympy import denom, S, factorial
%o A341233 def A341233(n):
%o A341233 return denom(sum((1-S(2)**(2-k))/factorial(k) for k in range(2,n+1)))
%o A341233 (Python)
%o A341233 from math import factorial
%o A341233 from fractions import Fraction
%o A341233 def a(n):
%o A341233 s = sum(Fraction(2**k-4, 2**k*factorial(k)) for k in range(2, n+1))
%o A341233 return s.denominator
%o A341233 print([a(n) for n in range(1, 21)]) # _Michael S. Branicky_, Feb 07 2021
%Y A341233 Cf. A248788, A341232 (numerators).
%K A341233 nonn,frac
%O A341233 1,3
%A A341233 _Pontus von Brömssen_, Feb 07 2021