cp's OEIS Frontend

A199935 Size (b^3_n) of unit sphere in a certain graph (see Hazama article for precise definition).

%I A199935 #24 Jul 27 2021 04:07:27
%S A199935 0,0,2,5,9,14,22,36,60,99,161,260,420,680,1102,1785,2889,4674,7562,
%T A199935 12236,19800,32039,51841,83880,135720,219600,355322,574925,930249,
%U A199935 1505174,2435422,3940596,6376020,10316619,16692641,27009260,43701900,70711160,114413062,185124225
%N A199935 Size (b^3_n) of unit sphere in a certain graph (see Hazama article for precise definition).
%H A199935 Vincenzo Librandi, <a href="/A199935/b199935.txt">Table of n, a(n) for n = 2..1000</a>
%H A199935 Fumio Hazama, <a href="http://dx.doi.org/10.1016/j.disc.2011.06.008">Spectra of graphs attached to the space of melodies</a>, Discr. Math., 311 (2011), 2368-2383. See Table 2.1.
%H A199935 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1,1,-1).
%F A199935 a(n) = 2*A130578(n-1) - A130578(n-2).
%F A199935 G.f.: -x^4*(-2+x) / ( (x-1)*(x^2-x+1)*(x^2+x-1) ). - _R. J. Mathar_, Nov 15 2011
%F A199935 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-4) - a(n-5), with a(2)=0, a(3)=0, a(4)=2, a(5)=5, a(6)=9. - _Harvey P. Dale_, Jul 04 2013
%t A199935 CoefficientList[Series[-x^2*(-2+x)/((x-1)*(x^2-x+1)*(x^2+x-1)),{x,0,50}],x] (* _Vincenzo Librandi_, Jul 10 2012 *)
%t A199935 LinearRecurrence[{3,-3,1,1,-1},{0,0,2,5,9},40] (* _Harvey P. Dale_, Jul 04 2013 *)
%K A199935 nonn,easy
%O A199935 2,3
%A A199935 _N. J. A. Sloane_, Nov 12 2011