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 A112094 #13 Jan 05 2025 19:51:38
%S A112094 1,2,8,120,672,5600,79200,50450400,201801600,10291881600,17776886400,
%T A112094 2151003254400,3805621142400,643149973065600,643149973065600,
%U A112094 31085582031504000,226741892465088000,65528406922410432000,31039771700089152000,414598230598090803264000,16583929223923632130560
%N A112094 Denominator of 3*Sum_{i=1..n} 1/(i^2*C(2*i,i)).
%H A112094 C. Elsner, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Papers1/43-1/paper43-1-5.pdf">On recurrence formulas for sums involving binomial coefficients</a>, Fib. Q., 43,1 (2005), 31-45.
%F A112094 3*Sum_{i >= 1} 1/(i^2*C(2*i, i)) = zeta(2) = Pi^2/6.
%e A112094 0, 3/2, 13/8, 197/120, 1105/672, 9211/5600, 130277/79200, 82987349/50450400, ... -> Pi^2/6.
%o A112094 (PARI) a(n) = denominator(3*sum(i=1, n, 1/(i^2*binomial(2*i, i)))); \\ _Michel Marcus_, Mar 10 2016
%Y A112094 Cf. A112093.
%K A112094 nonn,frac
%O A112094 0,2
%A A112094 _N. J. A. Sloane_, Nov 30 2005