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 A372976 #43 Dec 09 2024 15:16:03
%S A372976 0,3,20,27,64,75,132,147,224,243,340,363,480,507,644,675,832,867,1044,
%T A372976 1083,1280,1323,1540,1587,1824,1875,2132,2187,2464,2523,2820,2883,
%U A372976 3200,3267,3604,3675,4032,4107,4484,4563,4960,5043,5460,5547,5984,6075,6532,6627,7104
%N A372976 Number of minimum edge covers in the n-double cone graph.
%H A372976 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DoubleConeGraph.html">Double Cone Graph</a>.
%H A372976 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimumEdgeCover.html">Minimum Edge Cover</a>.
%H A372976 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).
%F A372976 a(n) = 3*n^2 + 4*n if (n mod 2 = 0), otherwise 3*n^2. - _Detlef Meya_, Jun 20 2024
%F A372976 From _Eric W. Weisstein_, Dec 09 2024: (Start)
%F A372976 G.f.: x*(-3-17*x-x^2-3*x^3)/((-1+x)^3*(1+x)^2).
%F A372976 a(n) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). (End)
%t A372976 a[n_] := If[Mod[n, 2] == 0, 3*n^2 + 4*n, 3*n^2]; Table[a[n], {n, 3, 44}] (* _Detlef Meya_, Jun 20 2024 *)
%t A372976 Table[n (2 + 2 (-1)^n + 3 n), {n, 0, 20}] (* _Eric W. Weisstein_, Dec 09 2024 *)
%t A372976 LinearRecurrence[{1, 2, -2, -1, 1}, {3, 20, 27, 64, 75}, {0, 20}] (* _Eric W. Weisstein_, Dec 09 2024 *)
%t A372976 CoefficientList[Series[(x (-3 - 17 x - x^2 - 3 x^3))/((-1 + x)^3 (1 + x)^2), {x, 0, 20}], x] (* _Eric W. Weisstein_, Dec 09 2024 *)
%Y A372976 Cf. A364741.
%K A372976 nonn,easy
%O A372976 0,2
%A A372976 _Eric W. Weisstein_, May 26 2024
%E A372976 a(10) and beyond from _Detlef Meya_, Jun 20 2024
%E A372976 Offset changed to 0 and a(0)-a(2) added using the formula/recurrence by _Eric W. Weisstein_, Dec 09 2024