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 A095308 #12 Aug 30 2024 11:32:41
%S A095308 1,1,5,6,21,28,84,121,331,507,1300,2093,5110,8568,20129,34885,79477,
%T A095308 141494,314489,572264,1246784,2309385,4950751,9303411,19684692,
%U A095308 37427313,78354346,150402700,312168761,603861897,1244620149
%N A095308 Number of walks of length n between two nodes at distance 3 in the cycle graph C_7.
%C A095308 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=7 and k=3.
%H A095308 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1, 4, -3, -2).
%F A095308 a(n) = (2^n/7)*Sum_{r=0..6} cos(6*Pi*r/7)*cos(2*Pi*r/7)^n.
%F A095308 G.f.: x^3/((-1 + 2x)*(-1 - x + 2x^2 + x^3)).
%F A095308 a(n) = a(n-1) + 4*a(n-2) - 3*a(n-3) - 2*a(n-4).
%Y A095308 Partial sums of A095307.
%K A095308 nonn
%O A095308 3,3
%A A095308 _Herbert Kociemba_, Jul 03 2004