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 A290924 #6 Nov 10 2022 15:29:34
%S A290924 1,5,23,104,469,2115,9539,43024,194053,875245,3947651,17805240,
%T A290924 80307649,362214635,1633710407,7368586016,33234813001,149900237685,
%U A290924 676100727791,3049442757256,13754017334317,62035266076915,279800013602699,1261992614249520,5692013155802701
%N A290924 a(n) = (1/2)*A290923(n).
%H A290924 Clark Kimberling, <a href="/A290924/b290924.txt">Table of n, a(n) for n = 0..1000</a>
%H A290924 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (6, -8, 6, -1)
%F A290924 G.f.: (1 - x + x^2)/(1 - 6 x + 8 x^2 - 6 x^3 + x^4).
%F A290924 a(n) = 6*a(n-1) - 8*a(n-2) + 6*a(n-3) - a(n-4).
%t A290924 z = 60; s = x/(1 - x)^2; p = 1 - 2 s - 2 s^2;
%t A290924 Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)
%t A290924 u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A290923 *)
%t A290924 u/2 (* A290924 *)
%t A290924 LinearRecurrence[{6,-8,6,-1},{1,5,23,104},30] (* _Harvey P. Dale_, Nov 10 2022 *)
%Y A290924 Cf. A000027, A290890.
%K A290924 nonn,easy
%O A290924 0,2
%A A290924 _Clark Kimberling_, Aug 19 2017