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 A095367 #17 Aug 29 2024 02:40:40
%S A095367 1,0,4,0,15,1,56,9,210,56,792,299,3003,1470,11441,6868,43776,31008,
%T A095367 168151,136629,648208,591261,2507046,2523676,9726080,10656387,
%U A095367 37839375,44612702,147600981,185477216,577147212,766744608,2261792303
%N A095367 Number of walks of length n between two nodes at distance 2 in the cycle graph C_9.
%C A095367 In general (2^n/m)*Sum_{r=0..m-1} cos(2*Pi*k*r/m)*cos(2*Pi*r/m)^n is the number of walks of length n between two nodes at distance k in the cycle graph C_m. Here we have m=9 and k=2.
%H A095367 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,5,-4,-5,2).
%F A095367 a(n) = (2^n/9)*Sum_{r=0..8} cos(4*Pi*r/9)*cos(2*Pi*r/9)^n.
%F A095367 G.f.: x^2(-1+x+x^2)/((1+x)*(-1+2x)*(1-3x^2+x^3));
%F A095367 a(n) = a(n-1) + 5*a(n-2) - 4*a(n-3) - 5*a(n-4) + 2*a(n-5).
%Y A095367 Cf. A095364, A095368, A095369.
%K A095367 nonn,easy
%O A095367 2,3
%A A095367 _Herbert Kociemba_, Jul 03 2004