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 A348224 #19 Dec 14 2024 07:17:39
%S A348224 0,0,3,3,3,6,9,9,15,18,18,24,29,30,39,44,45,54,62,63,75,83,84,96,106,
%T A348224 108,123,133,135,150,163,165,183,196,198,216,231,234,255,270,273,294,
%U A348224 312,315,339,357,360,384,404,408,435,455,459,486,509,513,543,566
%N A348224 Lower matching number of the n-triangular honeycomb acute knight graph.
%H A348224 Stan Wagon, <a href="http://www.jstor.org/stable/10.4169/college.math.j.45.4.278">Graph Theory Problems from Hexagonal and Traditional Chess</a>., The College Mathematics Journal, Vol. 45, No. 4, September 2014, pp. 278-287.
%H A348224 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LowerMatchingNumber.html">Lower Matching Number</a>.
%H A348224 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularHoneycombAcuteKnightGraph.html">Triangular Honeycomb Acute Knight Graph</a>.
%H A348224 <a href="/index/Rec#order_16">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1,0,0,0,0,0,0,0,1,-1,0,-1,1).
%F A348224 G.f.: x^3*(-3-3*x^4-3*x^6-2*x^10-x^11)/((-1+x)^3*(1+x+x^2)^2*(1+x^3+x^6+x^9)).
%F A348224 a(n) = a(n-1)+a(n-3)-a(n-4)+a(n-12)-a(n-13)-a(n-15)+a(n-16).
%t A348224 LinearRecurrence[{1, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, -1, 1}, {0, 0, 3, 3, 3, 6, 9, 9, 15, 18, 18, 24, 29, 30, 39, 44}, 20]
%t A348224 CoefficientList[Series[x^2 (-3 - 3 x^4 - 3 x^6 - 2 x^10 - x^11)/((-1 + x)^3 (1 + x + x^2)^2 (1 + x^3 + x^6 + x^9)), {x, 0, 20}], x]
%Y A348224 Cf. A289143 (matching number of the n-triangular honeycomb acute knight graph).
%K A348224 nonn,easy
%O A348224 1,3
%A A348224 _Eric W. Weisstein_, Oct 08 2021
%E A348224 a(16) and beyond from _Eric W. Weisstein_, Dec 07-08 2024