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 A008726 #47 Sep 08 2022 08:44:36
%S A008726 1,2,3,4,5,6,7,8,10,12,14,16,18,20,22,24,27,30,33,36,39,42,45,48,52,
%T A008726 56,60,64,68,72,76,80,85,90,95,100,105,110,115,120,126,132,138,144,
%U A008726 150,156,162,168,175,182,189,196,203,210,217,224,232,240,248,256,264,272,280
%N A008726 Molien series 1/((1-x)^2*(1-x^8)) for 3-dimensional group [2,n] = *22n.
%H A008726 Vincenzo Librandi, <a href="/A008726/b008726.txt">Table of n, a(n) for n = 0..1000</a>
%H A008726 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=191">Encyclopedia of Combinatorial Structures 191</a>
%H A008726 <a href="/index/Mo#Molien">Index entries for Molien series</a>
%H A008726 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,1,-2,1).
%F A008726 G.f.: 1/((1-x)^2*(1-x^8)).
%F A008726 From _Mitch Harris_, Sep 08 2008: (Start)
%F A008726 a(n) = Sum_{j=0..n+8} floor(j/8).
%F A008726 a(n-8) = (1/2)*floor(n/8)*(2*n-6-8*floor(n/8)). (End)
%F A008726 a(n) = 2*a(n-1) - a(n-2) + a(n-8) - 2*a(n-9) + a(n-10). - _R. J. Mathar_, Apr 20 2010
%p A008726 seq(coeff(series(1/(1-x)^2/(1-x^8), x, n+1), x, n), n=0..80);
%t A008726 CoefficientList[Series[1/((1-x)^2*(1-x^8)), {x,0,80}], x] (* _Vincenzo Librandi_, Jun 11 2013 *)
%t A008726 LinearRecurrence[{2,-1,0,0,0,0,0,1,-2,1}, {1,2,3,4,5,6,7,8,10,12}, 80] (* _Harvey P. Dale_, Jan 07 2015 *)
%o A008726 (PARI) my(x='x+O('x^80)); Vec(1/((1-x)^2*(1-x^8))) \\ _G. C. Greubel_, Sep 09 2019
%o A008726 (Magma) R<x>:=PowerSeriesRing(Integers(), 80); Coefficients(R!( 1/((1-x)^2*(1-x^8)) )); // _G. C. Greubel_, Sep 09 2019
%o A008726 (Sage)
%o A008726 def A008726_list(prec):
%o A008726 P.<x> = PowerSeriesRing(ZZ, prec)
%o A008726 return P(1/((1-x)^2*(1-x^8))).list()
%o A008726 A008726_list(80) # _G. C. Greubel_, Sep 09 2019
%o A008726 (GAP) a:=[1,2,3,4,5,6,7,8,10,12];; for n in [11..80] do a[n]:=2*a[n-1] -a[n-2]+a[n-8]-2*a[n-9]+a[n-10]; od; a; # _G. C. Greubel_, Sep 09 2019
%Y A008726 Cf. A001840, A001972, A008724, A008725, A008732. - _Vladimir Joseph Stephan Orlovsky_, Mar 14 2010
%K A008726 nonn,easy
%O A008726 0,2
%A A008726 _N. J. A. Sloane_
%E A008726 More terms from _Vladimir Joseph Stephan Orlovsky_, Mar 14 2010
%E A008726 Minor edits by _Jon E. Schoenfield_, Mar 28 2014