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 A336454 #11 Jul 26 2020 12:23:20
%S A336454 1,1,3,1,15,3,21,3,15,5,33,3,1365,105,15,3,255,15,1995,105,1155,165,
%T A336454 345,15,1365,273,21,7,435,15,7161,231,19635,1785,105,3,959595,25935,
%U A336454 1365,105,47355,1155,49665,1155,2415,2415,4935,105,23205,3315,7293,429,8745
%N A336454 a(n) = denominator(2^n*Sum_{k=0..n} binomial(n, k)*Bernoulli(k, 1/2)*x^(n-k)).
%p A336454 Bcp := n -> 2^n*add(binomial(n, k)*bernoulli(k, 1/2)*x^(n-k), k=0..n):
%p A336454 a := n -> denom(Bcp(n)): seq(a(n), n=0..52);
%Y A336454 Cf. A336517/A285865 (coefficients of polynomials).
%K A336454 nonn,frac
%O A336454 0,3
%A A336454 _Peter Luschny_, Jul 24 2020