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 A136494 #14 Jul 29 2023 03:14:29
%S A136494 1,1,1,2,2,2,2,6,6,4,4,6,4,6,6,24,24,12,12,12,12,12,12,24,12,12,12,24,
%T A136494 12,24,24,120,120,48,48,36,48,36,36,48,48,36,36,48,36,48,48,120,48,36,
%U A136494 36,48,36,48,48,120,36,48,48,120,48,120,120,720,720
%N A136494 Number of permutation symmetries in the binary expansion of n.
%H A136494 Andrew Howroyd, <a href="/A136494/b136494.txt">Table of n, a(n) for n = 0..1023</a>
%F A136494 a(n) = A093659(n) * A139329(n).
%F A136494 a(n) = A000120(n)! * A080791(n)!.
%e A136494 a(14) = 6 because there are 3! permutation symmetries of 1's * the 0! permutation symmetries of 0's.
%t A136494 a[n_] := Times @@ (DigitCount[n, 2]!); Array[a, 65, 0] (* _Amiram Eldar_, Jul 29 2023 *)
%o A136494 (PARI) a(n) = {if(n==0, 1, my(w=hammingweight(n)); w!*(1+logint(n,2)-w)!)} \\ _Andrew Howroyd_, Jan 12 2020
%Y A136494 Cf. A000120, A080791, A093659, A139329.
%K A136494 base,nonn
%O A136494 0,4
%A A136494 _Max Sills_, Apr 13 2008
%E A136494 Terms a(32) and beyond from _Andrew Howroyd_, Jan 12 2020