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 A276668 #6 Sep 25 2016 04:00:02 %S A276668 1,12,120,56,16,88,208,16,544,152,16,368,32,16,928,992,64,8,592,16, %T A276668 1312,688,32,1504,64,16,1696,32,64,1888,3904,64,128,536,16,1136,2336, %U A276668 16,32,2528,64,1328,32,32,5696,32,64,64,12416,16,3232,3296,64,3424,6976 %N A276668 a(n) = denominator(b(2*n)) with b(n) = n!*Bernoulli(n,1/2)/(n*(n-1)) for n>=2, b(0)=1, b(1)=0. %p A276668 b := n -> `if`(n<2, 1-n, (n-2)!*bernoulli(n,1/2)): %p A276668 a := n -> denom(b(2*n)): %p A276668 seq(a(n), n=0..54); %Y A276668 Cf. A276667 (numerators). %K A276668 nonn,frac %O A276668 0,2 %A A276668 _Peter Luschny_, Sep 24 2016