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 A213595 #7 Jan 08 2025 13:01:25 %S A213595 1,1,3,1,9,3,1,3,3,3,1,3,3,3,15,3,3,9,3,9,1,1,15,27,9,3,15,1,5,5,3,9, %T A213595 9,9,3,3,1,3,45,9,15,1,15,15,15,45,9,81,9,5,5,1,25,5,3,3,5,5,3,15,27, %U A213595 9,21,3,81,9,3,15,1,3,75,81,9,9,135,27,25,15 %N A213595 a(n) = A048784(n) / 2^A213594(n). %C A213595 a(n) = tau(binomial(2*n,n)) / 2^k, where tau = number of divisors (A000005) and k is the greatest possible integer. %e A213595 a(7) = 1 because A048784(7) / 2^5 = 32 / 32 = 1 is an integer. %p A213595 with(numtheory): for n from 1 to 100 do:ii:=0:for k from 500 by -1 to 1 while(ii=0) do: x:=evalf(tau(binomial(2*n,n))/2^k):if x=floor(x) then ii:=1: printf(`%d, `,floor(x)):else fi:od:od: %Y A213595 Cf. A048784, A213594. %K A213595 nonn %O A213595 1,3 %A A213595 _Michel Lagneau_, Jun 15 2012