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 A291390 #4 Sep 06 2017 21:13:31
%S A291390 2,17,130,940,6550,44475,296250,1944375,12612500,81035000,516537500,
%T A291390 3270615625,20591031250,128998328125,804673593750,5000444062500,
%U A291390 30969644531250,191231146484375,1177627753906250,7234317013671875,44342955390625000,271252632343750000
%N A291390 a(n) = (1/5)*A291389(n).
%H A291390 Clark Kimberling, <a href="/A291390/b291390.txt">Table of n, a(n) for n = 0..1000</a>
%H A291390 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (10, -15, -50, -25)
%F A291390 G.f.: -(((1 + x) (-2 + 5 x + 5 x^2))/(-1 + 5 x + 5 x^2)^2).
%F A291390 a(n) = 10*a(n-1) - 15*a(n-2) - 50*a(n-3) - 25*a(n-4) for n >= 5.
%t A291390 z = 60; s = x + x^2; p = (1 - 5 s)^2;
%t A291390 Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A019590 *)
%t A291390 u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A291389 *)
%t A291390 u / 5 (* A291390 *)
%Y A291390 Cf. A019590, A291382, A291389.
%K A291390 nonn,easy
%O A291390 0,1
%A A291390 _Clark Kimberling_, Sep 06 2017