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 A357286 #6 Dec 10 2023 09:24:12
%S A357286 0,0,0,0,0,0,0,1,4,13,38,99,240,565,1274,2799,6052,12857,26958,56099,
%T A357286 115704,237133,484002,983543,1992012,4026017,8118262,16342347,
%U A357286 32860832,65998837,132437322,265603743,532348916,1066505545,2135992990,4276649971,8560661832
%N A357286 a(n) = (1/8)*A357285.
%H A357286 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (4, -3, -2, -6, 8, 24, -40, 16).
%F A357286 a(n) = 4*a(n-1) - 3*a(n-2) - 6*a(n-3) + 10*a(n-4) - 4*a(n-5).
%F A357286 G.f.: -(x^7/((-1 + x)^2 (-1 + 2 x) (-1 + 2 x^2) (-1 + 4 x^3))).
%t A357286 s[n_] := s[n] = Select[Subsets[Range[n]], Length[#] >= 3 &];
%t A357286 a[n_] := Select[s[n], #[[1]] + #[[2]] + #[[3]] < #[[-1]] &]
%t A357286 (1/8)*Table[Length[a[n]], {n, 0, 18}]
%Y A357286 Cf. A357285.
%K A357286 nonn,easy
%O A357286 0,9
%A A357286 _Clark Kimberling_, Oct 02 2022