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 A288029 #17 May 29 2025 10:40:25
%S A288029 1,2,6,17,45,120,324,873,2349,6322,17018,45809,123305,331904,893400,
%T A288029 2404801,6473097,17423890,46900574,126244129,339816309,914696984,
%U A288029 2462126012,6627401865,17839239445,48018585634,129253524146,347916817697,936501444241,2520817938240
%N A288029 Number of minimal edge covers in the ladder graph P_2 X P_n.
%H A288029 Andrew Howroyd, <a href="/A288029/b288029.txt">Table of n, a(n) for n = 1..200</a>
%H A288029 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LadderGraph.html">Ladder Graph</a>
%H A288029 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimalEdgeCover.html">Minimal Edge Cover</a>
%H A288029 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2, 1, 2, 1, 0, -1).
%F A288029 a(n) = 2*a(n-1)+a(n-2)+2*a(n-3)+a(n-4)-a(n-6) for n>6.
%F A288029 G.f.: x*(1+x^2+x^3-x^5)/((1+x^2)*(1-2*x-2*x^2+x^4)).
%t A288029 Table[(RootSum[1 - 2 #^2 - 2 #^3 + #^4 &, 94 #^n + 33 #^(n + 1) - 7 #^(n + 2) + 8 #^(n + 3) &] + 182 (2 Cos[n Pi/2] + Sin[n Pi/2]))/910, {n, 20}] (* _Eric W. Weisstein_, Aug 03 2017 *)
%t A288029 LinearRecurrence[{2, 1, 2, 1, 0, -1}, {1, 2, 6, 17, 45, 120}, 20] (* _Eric W. Weisstein_, Aug 03 2017 *)
%t A288029 CoefficientList[Series[(1 + x^2 + x^3 - x^5)/(1 - 2 x - x^2 - 2 x^3 - x^4 + x^6), {x, 0, 20}], x] (* _Eric W. Weisstein_, Aug 03 2017 *)
%o A288029 (PARI)
%o A288029 Vec((1+x^2+x^3-x^5)/((1+x^2)*(1-2*x-2*x^2+x^4))+O(x^20))
%Y A288029 Row 2 of A288025.
%Y A288029 Cf. A288030, A288027.
%K A288029 nonn
%O A288029 1,2
%A A288029 _Andrew Howroyd_, Jun 04 2017