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 A034662 #31 Sep 08 2022 08:44:52
%S A034662 6,42,546,9198,170898,3304182,65019786,1290094638,25700456418,
%T A034662 513002215782,10250010815226,204900053024478,4097000260921938,
%U A034662 81930001287820182,1638500006371967466,32769000031591352718,655370000156882923458
%N A034662 Sum of n-th powers of divisors of 20.
%H A034662 T. D. Noe, <a href="/A034662/b034662.txt">Table of n, a(n) for n = 0..200</a>
%H A034662 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (42,-609,3948,-12180,16800,-8000).
%F A034662 a(n) = (1 + 2^n + 4^n)*(1 + 5^n). - _Bruno Berselli_, Apr 17 2014
%F A034662 G.f.: -6*(2800*x^5 -4060*x^4 +1974*x^3 -406*x^2 +35*x -1) / ((x -1)*(2*x -1)*(4*x -1)*(5*x -1)*(10*x -1)*(20*x -1)). - _Colin Barker_, Apr 20 2014
%t A034662 Total[#^Range[0, 20]&/@Divisors[20]] (* _Vincenzo Librandi_, Apr 17 2014 *)
%t A034662 Table[(1 + 2^n + 4^n) (1 + 5^n), {n, 0, 20}] (* _Bruno Berselli_, Apr 17 2014 *)
%o A034662 (Sage) [sigma(20,n) for n in range(0,16)] # _Zerinvary Lajos_, Jun 04 2009
%o A034662 (Magma) [DivisorSigma(n,20): n in [0..20]]; // _Vincenzo Librandi_, Apr 17 2014
%K A034662 nonn,easy
%O A034662 0,1
%A A034662 _N. J. A. Sloane_