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 A327493 #12 Oct 03 2019 06:16:53
%S A327493 1,4,8,32,128,512,1024,4096,32768,131072,262144,1048576,4194304,
%T A327493 16777216,33554432,134217728,2147483648,8589934592,17179869184,
%U A327493 68719476736,274877906944,1099511627776,2199023255552,8796093022208,70368744177664,281474976710656,562949953421312
%N A327493 a(n) = 2^A327492(n).
%F A327493 a(n) = denominator(b(n)) where b(n) = n!/(2^n*floor(n/2)!)^2 is the normalized swinging factorial (A056040).
%p A327493 A327493 := n -> 2^(A327492_list(n+1)[n+1]):
%p A327493 seq(A327493(n), n = 0..26);
%o A327493 (PARI) seq(n)={my(a=vector(n+1)); a[1]=1; for(n=1, n, a[n+1] = a[n] * 2^if(n%4, n%2 + 1, valuation(n,2))); a} \\ _Andrew Howroyd_, Sep 28 2019
%o A327493 (PARI) a(n)={ denominator(sum(j=0, n, j!/(2^j*(j\2)!)^2)) } \\ _Andrew Howroyd_, Sep 28 2019
%o A327493 (Julia)
%o A327493 bitcount(n) = sum(digits(n, base = 2))
%o A327493 A327493(n) = 2^(2n - bitcount(n) + mod(n, 2))
%o A327493 [A327493(n) for n in 0:26] |> println # _Peter Luschny_, Oct 03 2019
%Y A327493 Cf. A327492, A327491, A327494, A327495, A056040.
%K A327493 nonn
%O A327493 0,2
%A A327493 _Peter Luschny_, Sep 27 2019