%I #34 Feb 03 2022 00:33:41
%S 1,2,4,6,10,14,20,26,35,44,57,70,88,106,130,154,185,216,255,294,344,
%T 394,456,518,595,672,765,858,970,1082,1216,1350,1509,1668,1855,2042,
%U 2260,2478,2730,2982,3274,3566,3901,4236,4620,5004,5440,5876,6370,6864
%N Expansion of 1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20).
%H Vincenzo Librandi, <a href="/A001307/b001307.txt">Table of n, a(n) for n = 0..1000</a>
%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=200">Encyclopedia of Combinatorial Structures 200</a>
%H <a href="/index/Rec#order_38">Index entries for linear recurrences with constant coefficients</a>, signature (2, 0, -2, 2, -2, 0, 2, -1, 0, 1, -2, 0, 2, -2, 2, 0, -2, 1, 0, 1, -2, 0, 2, -2, 2, 0, -2, 1, 0, -1, 2, 0, -2, 2, -2, 0, 2, -1).
%F G.f.: 1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20).
%t CoefficientList[Series[1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20),{x,0,50}],x] (* _Vincenzo Librandi_, Feb 24 2012 *)
%t LinearRecurrence[{2,0,-2,2,-2,0,2,-1,0,1,-2,0,2,-2,2,0,-2,1,0,1,-2,0,2,-2,2,0,-2,1,0,-1,2,0,-2,2,-2,0,2,-1},{1,2,4,6,10,14,20,26,35,44,57,70,88,106,130,154,185,216,255,294,344,394,456,518,595,672,765,858,970,1082,1216,1350,1509,1668,1855,2042,2260,2478},50] (* _Harvey P. Dale_, Aug 12 2021 *)
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_