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 A071246 #26 Aug 07 2024 02:26:06
%S A071246 0,0,4,23,76,190,400,749,1288,2076,3180,4675,6644,9178,12376,16345,
%T A071246 21200,27064,34068,42351,52060,63350,76384,91333,108376,127700,149500,
%U A071246 173979,201348,231826,265640,303025,344224,389488,439076,493255,552300,616494
%N A071246 a(n) = n*(n - 1)*(2*n^2 + n + 2)/6.
%D A071246 T. A. Gulliver, Sequences from Arrays of Integers, Int. Math. Journal, Vol. 1, No. 4, pp. 323-332, 2002.
%H A071246 Vincenzo Librandi, <a href="/A071246/b071246.txt">Table of n, a(n) for n = 0..2000</a>
%H A071246 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A071246 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5), n > 4, a(0)=0, a(1)=0, a(2)=4, a(3)=23, a(4)=76. - _Yosu Yurramendi_, Sep 03 2013
%F A071246 From _Indranil Ghosh_, Apr 05 2017: (Start)
%F A071246 G.f.: x^2*(4 + 3*x + x^2)/(1 - x)^5.
%F A071246 E.g.f.: exp(x)*x^2*(4+x)*(3+2*x)/6. (End)
%t A071246 CoefficientList[Series[-(4x^2 + 3x^3 + x^4)/(x - 1)^5, {x, 0, 50}], x] (* or *) Table[n*(n - 1)*(2*n^2 + n + 2)/6, {n, 0, 50}] (* _Indranil Ghosh_, Apr 05 2017 *)
%o A071246 (Magma) [n*(n-1)*(2*n^2+n+2)/6: n in [0..40]]; // _Vincenzo Librandi_, Jun 14 2011
%o A071246 (PARI) a(n) = n*(n - 1)*(2*n^2 + n + 2)/6; \\ _Indranil Ghosh_, Apr 05 2017
%o A071246 (Python) def a(n): return n*(n - 1)*(2*n**2 + n + 2)/6 # _Indranil Ghosh_, Apr 05 2017
%o A071246 (SageMath)
%o A071246 def A071246(n): return binomial(n,2)*(2+n+2*n^2)//3
%o A071246 [A071246(n) for n in range(41)] # _G. C. Greubel_, Aug 07 2024
%Y A071246 Cf. A071239, A071244, A071245.
%K A071246 nonn,easy
%O A071246 0,3
%A A071246 _N. J. A. Sloane_, Jun 12 2002