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 A290910 #9 Feb 26 2018 16:58:35
%S A290910 0,1,4,15,60,240,956,3809,15180,60495,241080,960736,3828664,15257745,
%T A290910 60804180,242312895,965649716,3848244944,15335777460,61115150865,
%U A290910 243552156060,970588338271,3867926023024,15414209227200,61427712082800,244797754857825
%N A290910 a(n) = (1/5)*A290909(n), n>= 0.
%H A290910 Clark Kimberling, <a href="/A290910/b290910.txt">Table of n, a(n) for n = 0..1000</a>
%H A290910 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4, -1, 4, -1)
%F A290910 G.f.: x/(1 - 4 x + x^2 - 4 x^3 + x^4).
%F A290910 a(n) = 4*a(n-1) - a(n-2) + 4*a(n-3) - a(n-4).
%F A290910 a(n) = (1/5)*A290909(n) for n >= 0.
%t A290910 z = 60; s = x/(1 - x)^2; p = 1 - 5 s^2;
%t A290910 Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)
%t A290910 u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A290909 *)
%t A290910 u/5 (* A290910 *)
%t A290910 LinearRecurrence[{4,-1,4,-1},{0,1,4,15},30] (* _Harvey P. Dale_, Feb 19 2018 *)
%o A290910 (PARI) concat([0], Vec(1/(1 - 4*x + x^2 - 4*x^3 + x^4) + O(x^30))) \\ _Andrew Howroyd_, Feb 26 2018
%Y A290910 Cf. A000027, A290890, A290909.
%K A290910 nonn,easy
%O A290910 0,3
%A A290910 _Clark Kimberling_, Aug 18 2017