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 A056648 #16 Sep 28 2024 07:37:54
%S A056648 1,1,1,1,1,2,1,1,2,4,1,2,2,1,2,2,1,2,1,2,2,1,1,2,4,2,4,2,2,4,2,2,1,2,
%T A056648 2,4,4,2,2,4,2,1,2,1,2,4,4,8,8,4,4,2,2,4,2,1,1,2,1,2,2,2,4,4,2,4,2,4,
%U A056648 4,2,1,2,2,1,4,2,4,8,2,4,8,4,2,1,2,4,8,4,2,4,4,8,4,4,8,16,8,4,4,2,1,2,2,1
%N A056648 a(n) = A034444(A056647(n)).
%C A056648 Previous name, "Number of unitary square divisors of central binomial coefficient", was incorrect. See A376555 for the correct sequence with this name. - _Amiram Eldar_, Sep 28 2024
%F A056648 a(n) = 2^r, where r = A001221(A000188(A001405(n))/A055229(A001405(n))).
%e A056648 a(28) = A034444(A056647(28)) = A034444(25) = 2.
%t A056648 A008833[n_] := First[Select[Reverse[Divisors[n]], IntegerQ[Sqrt[#]] &, 1]]; A055229[n_] := With[{sf = Times @@ Power @@@ ({#[[1]], Mod[#[[2]], 2]} & /@ FactorInteger[n])}, GCD[sf, n/sf]]; Table[2^(PrimeNu[ Sqrt[A008833[Binomial[n, Floor[n/2]]]]/A055229[Binomial[n, Floor[n/2]]]]), {n, 1, 25}] (* _G. C. Greubel_, May 20 2017 *)
%Y A056648 Cf. A000188, A001221, A001405, A008833, A034444, A055229, A056056, A056057, A056059, A056061, A376555.
%K A056648 nonn
%O A056648 1,6
%A A056648 _Labos Elemer_, Aug 09 2000
%E A056648 Incorrect name replaced with a formula by _Amiram Eldar_, Sep 28 2024