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 A179504 #15 Jul 09 2022 11:10:21
%S A179504 1,3,21,252,4369,103158,3037530,106237176,4311810305,198756808749,
%T A179504 10250010815226,584603613083988,36529334450076658,2481455748310337022,
%U A179504 182070232515259616850,14349345894391097803752
%N A179504 a(n) = sigma(2n,n) for n>0 with a(0)=1.
%C A179504 sigma(n,k) denotes the sum of the k-th powers of the divisors of n.
%H A179504 Michel Marcus, <a href="/A179504/b179504.txt">Table of n, a(n) for n = 0..100</a>
%F A179504 After initial term, equals the logarithmic derivative of A156360.
%F A179504 Conjecture: a(n) = A023887(n)*((2^n - 1)/(2^(n*(A007814(n) + 1)) - 1) + 2^n) for n > 0. - _Velin Yanev_, Jul 08 2017
%F A179504 a(n) ~ (2*n)^n. - _Vaclav Kotesovec_, Aug 21 2017
%t A179504 Table[If[n == 0, 1, DivisorSigma[n, 2 n]], {n, 0, 15}] (* _Michael De Vlieger_, Jul 12 2017 *)
%o A179504 (PARI) a(n)=if(n==0,1,sigma(2*n,n))
%o A179504 (Python)
%o A179504 from sympy import divisor_sigma
%o A179504 def A179504(n): return divisor_sigma(n<<1,n) if n else 1 # _Chai Wah Wu_, Jul 08 2022
%K A179504 nonn
%O A179504 0,2
%A A179504 _Paul D. Hanna_, Sep 21 2010