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%I #26 Jun 13 2023 09:14:56
%S 0,0,0,0,0,4,12,28,56,100,168,264,396,572,800,1092,1456,1904,2448,
%T 3100,3876,4788,5852,7084,8500,10120,11960,14040,16380,19000,21924,
%U 25172,28768,32736,37100,41888,47124
%N a(n) = floor(n(n-1)(n-2)(n-3)/30).
%H Vincenzo Librandi, <a href="/A011940/b011940.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (4, -6, 4, -1, 1, -4, 6, -4, 1).
%F From _R. J. Mathar_, Apr 15 2010: (Start)
%F a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-5) - 4*a(n-6) + 6*a(n-7) - 4*a(n-8) + a(n-9).
%F G.f.: 4*x^5*(x^2-x+1) / ((1-x)^5*(x^4+x^3+x^2+x+1) ). (End)
%t CoefficientList[Series[4*x^5*(x^2-x+1)/((1-x)^5*(x^4+x^3+x^2+x+1)),{x,0,50}],x] (* _Vincenzo Librandi_, Jun 19 2012 *)
%t LinearRecurrence[{4,-6,4,-1,1,-4,6,-4,1},{0,0,0,0,0,4,12,28,56},40] (* _Harvey P. Dale_, Nov 13 2017 *)
%o (Magma) [Floor( n*(n-1)*(n-2)*(n-3)/30): n in [0..40]]; // _Vincenzo Librandi_, Jun 19 2012
%Y Equals 4 * A011795.
%K nonn,easy
%O 0,6
%A _N. J. A. Sloane_
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