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 A340243 #35 Jun 15 2022 10:49:07
%S A340243 2,6,30,189,1350,10395,58046625,1403325,21709437750,2292899734125,
%T A340243 80596287646875,640374140030625,8779111824511153125,
%U A340243 443779279041223125,20913098524817639765625,195202717402382161174828125,2015813566807172297008593750,367589532770719654160390625
%N A340243 a(n) = denominator((2*n-1)*zeta(2*n)/Pi^(2*n)).
%C A340243 For numerators a(n+1) see A046988.
%F A340243 a(n) = denominator((2*n-1)*2^(2*n-1)*Bernoulli(2*n)/(2*n)!). - _Peter Luschny_, Jan 12 2021
%e A340243 1/2, 1/6, 1/30, 1/189, 1/1350, 1/10395, 691/58046625, 2/1403325, 3617/21709437750, 43867/2292899734125, ...
%p A340243 a := n -> denom((2*n-1)*Zeta(2*n)/Pi^(2*n));
%p A340243 seq(a(n), n=0..17); # _Peter Luschny_, Jan 12 2021
%t A340243 Denominator[Table[(2 n - 1)*Zeta[2 n]/Pi^(2 n), {n, 0, 16}]]
%o A340243 (PARI) a(n) = denominator((2*n-1)*2^(2*n-1)*bernfrac(2*n)/(2*n)!); \\ _Michel Marcus_, Jun 15 2022
%Y A340243 Cf. A002432, A027642, A046988, A176289, A164555.
%K A340243 nonn,frac
%O A340243 0,1
%A A340243 _Artur Jasinski_, Jan 01 2021