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 A011887 #22 Oct 17 2024 08:25:16
%S A011887 0,0,0,1,4,12,24,42,67,100,144,198,264,343,436,546,672,816,979,1162,
%T A011887 1368,1596,1848,2125,2428,2760,3120,3510,3931,4384,4872,5394,5952,
%U A011887 6547,7180,7854,8568,9324,10123,10966
%N A011887 a(n) = floor( n*(n-1)*(n-2)/5 ).
%H A011887 Vincenzo Librandi, <a href="/A011887/b011887.txt">Table of n, a(n) for n = 0..1000</a>
%H A011887 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1,0,1,-3,3,-1).
%F A011887 From _R. J. Mathar_, Apr 15 2010: (Start)
%F A011887 a(n) = +3*a(n-1) -3*a(n-2) +a(n-3) +a(n-5) -3*a(n-6) +3*a(n-7) -a(n-8).
%F A011887 G.f.: x^3*(1+x+3*x^2-x^3+2*x^4) / ( (1-x)^4*(1+x+x^2+x^3+x^4) ). (End)
%t A011887 CoefficientList[Series[x^3*(1+x+3*x^2-x^3+2*x^4)/((1-x)^3*(1-x^5)),{x,0,50}] ,x] (* _Vincenzo Librandi_, Jul 07 2012 *)
%o A011887 (Magma) [Floor(n*(n-1)*(n-2)/5): n in [0..50]]; // _Vincenzo Librandi_, Jul 07 2012
%o A011887 (SageMath) [6*binomial(n,3)//5 for n in range(51)] # _G. C. Greubel_, Oct 16 2024
%Y A011887 Cf. A011886.
%K A011887 nonn,easy
%O A011887 0,5
%A A011887 _N. J. A. Sloane_