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 A376555 #7 Sep 28 2024 07:37:29 %S A376555 1,1,1,1,1,1,2,1,1,2,4,1,2,2,1,2,2,1,2,1,2,2,1,1,2,4,2,4,2,2,4,2,2,1, %T A376555 2,2,4,4,2,2,4,2,1,2,1,2,4,4,8,8,4,4,2,2,4,2,1,1,2,1,2,2,1,4,4,2,4,2, %U A376555 4,4,2,1,2,2,1,4,2,4,8,2,4,8,4,2,1,2,4 %N A376555 The number of unitary square divisors of binomial(n, floor(n/2)). %H A376555 Amiram Eldar, <a href="/A376555/b376555.txt">Table of n, a(n) for n = 0..10000</a> %F A376555 a(n) = A056624(A001405(n)). %t A376555 f[p_, e_] := 2^(1 - Mod[e, 2]); a[n_] := Times @@ f @@@ FactorInteger[Binomial[n, Floor[n/2]]]; Array[a, 100, 0] %o A376555 (PARI) a(n) = vecprod(apply(x -> 1 << (1 - x%2), factor(binomial(n, n\2))[, 2])); %Y A376555 Cf. A001405, A056061, A056624, A376553, A376554, A376556. %K A376555 nonn %O A376555 0,7 %A A376555 _Amiram Eldar_, Sep 28 2024