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 A291986 #17 Sep 15 2023 19:08:29
%S A291986 1,1,3,6,10,16,33,45,79,130,198,300,517,721,1155,1806,2674,3976,6441,
%T A291986 9045,13975,21370,31230,46020,72301,101881,154443,233286,338410,
%U A291986 496096,765393,1080765,1619359,2427250,3504438,5120220,7806037,11037601,16409235,24466686
%N A291986 Expansion of 1/((1-x)*(1-2*x^2)*(1-3*x^3)).
%H A291986 Seiichi Manyama, <a href="/A291986/b291986.txt">Table of n, a(n) for n = 0..6278</a>
%H A291986 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1, 2, 1, -3, -6, 6).
%t A291986 CoefficientList[Series[1/((1-x)(1-2x^2)(1-3x^3)),{x,0,40}],x] (* or *) LinearRecurrence[{1,2,1,-3,-6,6},{1,1,3,6,10,16},40] (* _Harvey P. Dale_, Sep 15 2023 *)
%o A291986 (PARI) Vec(1/((1-x)*(1-2*x^2)*(1-3*x^3)) + O(x^100))
%Y A291986 Cf. A291960, A291987, A291988.
%K A291986 nonn,easy
%O A291986 0,3
%A A291986 _Seiichi Manyama_, Sep 07 2017