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 A357288 #10 Oct 20 2022 12:44:47
%S A357288 0,0,0,0,0,0,1,2,5,12,23,42,85,144,251,454,753,1244,2183,3506,5725,
%T A357288 9736,15539,24926,41993,66228,105823,176138,277173,439648,729099,
%U A357288 1141430,1807713,2981900,4663991,7361890,12124173,18918072,29840739,49020942
%N A357288 a(n) = (1/4)*A357287(n).
%H A357288 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,0,-6,-4,16,-8).
%F A357288 a(n) = 2*a(n-1) + a(n-2) - 6*a(n-4) - 4*a(n-5) + 16*a(n-6) - 8*a(n-7).
%F A357288 G.f.: x^6/((-1 + x)^2 (-1 + 2 x^2) (-1 + 4 x^3)).
%t A357288 s[n_] := s[n] = Select[Subsets[Range[n]], Length[#] >= 3 &];
%t A357288 a[n_] := Select[s[n], #[[1]] + #[[2]] + #[[3]] == #[[-1]] &]
%t A357288 (1/4)*Table[Length[a[n]], {n, 0, 15}]
%Y A357288 Cf. A357287.
%K A357288 nonn,easy
%O A357288 0,8
%A A357288 _Clark Kimberling_, Oct 02 2022