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 A097869 #20 Sep 08 2022 08:45:14
%S A097869 1,1,2,2,6,7,11,12,21,25,34,38,54,63,79,88,113,129,154,170,206,231,
%T A097869 267,292,341,377,426,462,526,575,639,688,769,833,914,978,1078,1159,
%U A097869 1259,1340,1461,1561,1682,1782,1926,2047,2191,2312,2481,2625,2794,2938,3134,3303
%N A097869 Expansion of g.f.: (1+x^4+x^5+x^9)/((1-x)*(1-x^2)*(1-x^4)^2).
%C A097869 Molien series for group of order 128 acting on joint weight enumerators of a pair of binary self-dual codes is (1+x^8+x^10+x^18)/((1-x^2)*(1-x^4)*(1-x^8)^2).
%H A097869 G. C. Greubel, <a href="/A097869/b097869.txt">Table of n, a(n) for n = 0..1000</a>
%H A097869 F. J. MacWilliams, C. L. Mallows and N. J. A. Sloane, <a href="http://neilsloane.com/doc/gleason2.html">Generalizations of Gleason's theorem on weight enumerators of self-dual codes</a>, IEEE Trans. Inform. Theory, 18 (1972), 794-805; see p. 804, Sect. 5.4.1.
%H A097869 <a href="/index/Mo#Molien">Index entries for Molien series</a>
%H A097869 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,2,-4,2,0,-1,2,-1).
%F A097869 G.f.: (1+x^4)*(1-x+x^2-x^3+x^4)/( (1+x)^2*(1+x^2)^2*(1-x)^4 ). - _R. J. Mathar_, Dec 18 2014
%F A097869 From _Greg Dresden_, Jun 22 2021: (Start)
%F A097869 a(2*n) = (1/48)*(30 + 18*(-1)^n + 64*n + 12*n^2 + 8*n^3),
%F A097869 a(2*n+1) = (1/48)*(36 + 12*(-1)^n + 16*n + 8*n^2)*(1 + n). (End)
%p A097869 m:=55; S:=series((1+x^4)*(1+x^5)/((1-x)*(1-x^2)*(1-x^4)^2), x, m+1): seq(coeff(S, x, j), j=0..m); # _G. C. Greubel_, Feb 05 2020
%t A097869 CoefficientList[Series[(1+x^4)*(1+x^5)/((1-x)*(1-x^2)*(1-x^4)^2), {x,0,55}], x] (* _G. C. Greubel_, Feb 05 2020 *)
%t A097869 LinearRecurrence[{2,-1,0,2,-4,2,0,-1,2,-1},{1,1,2,2,6,7,11,12,21,25},60] (* _Harvey P. Dale_, Jun 19 2021 *)
%o A097869 (PARI) Vec( (1+x^4)*(1+x^5)/((1-x)*(1-x^2)*(1-x^4)^2) +O('x^55) ) \\ _G. C. Greubel_, Feb 05 2020
%o A097869 (Magma) R<x>:=PowerSeriesRing(Integers(), 55); Coefficients(R!( (1+x^4)*(1+x^5)/((1-x)*(1-x^2)*(1-x^4)^2) )); // _G. C. Greubel_, Feb 05 2020
%o A097869 (Sage)
%o A097869 def A097869_list(prec):
%o A097869 P.<x> = PowerSeriesRing(ZZ, prec)
%o A097869 return P( (1+x^4)*(1+x^5)/((1-x)*(1-x^2)*(1-x^4)^2) ).list()
%o A097869 A097869_list(55) # _G. C. Greubel_, Feb 05 2020
%Y A097869 Cf. A097870.
%K A097869 nonn
%O A097869 0,3
%A A097869 _N. J. A. Sloane_, Sep 02 2004