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 A033442 #31 Feb 16 2025 08:32:36
%S A033442 0,0,1,3,6,10,15,21,28,36,45,54,64,75,87,100,114,129,145,162,180,198,
%T A033442 217,237,258,280,303,327,352,378,405,432,460,489,519,550,582,615,649,
%U A033442 684,720,756,793,831,870,910,951,993,1036,1080,1125,1170,1216,1263
%N A033442 Number of edges in 10-partite Turán graph of order n.
%D A033442 Graham et al., Handbook of Combinatorics, Vol. 2, p. 1234.
%H A033442 Vincenzo Librandi, <a href="/A033442/b033442.txt">Table of n, a(n) for n = 0..1000</a>
%H A033442 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TuranGraph.html">Turán Graph</a> [_Reinhard Zumkeller_, Nov 30 2009]
%H A033442 Wikipedia, <a href="http://en.wikipedia.org/wiki/Tur%C3%A1n_graph">Turán graph</a> [_Reinhard Zumkeller_, Nov 30 2009]
%H A033442 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,0,1,-2,1).
%F A033442 a(n) = Sum_{k=0..n} A168184(k)*(n-k). [_Reinhard Zumkeller_, Nov 30 2009]
%F A033442 G.f.: -x^2*(x^2+x+1)*(x^6+x^3+1)/((x-1)^3*(x+1)*(x^4-x^3+x^2-x+1)*(x^4+x^3+x^2+x+1)). [_Colin Barker_, Aug 09 2012]
%F A033442 a(n) = Sum_{i=1..n} floor(9*i/10). - _Wesley Ivan Hurt_, Sep 12 2017
%t A033442 CoefficientList[Series[- x^2 (x^2 + x + 1) (x^6 + x^3 + 1)/((x - 1)^3 (x + 1) (x^4 - x^3 + x^2 - x + 1) (x^4 + x^3 + x^2 + x + 1)), {x, 0, 60}], x] (* _Vincenzo Librandi_, Oct 20 2013 *)
%Y A033442 Cf. A002620, A000212, A033436, A033437, A033438, A033439, A033440, A033441, A033443, A033444. [_Reinhard Zumkeller_, Nov 30 2009]
%K A033442 nonn,easy
%O A033442 0,4
%A A033442 _N. J. A. Sloane_
%E A033442 More terms from _Vincenzo Librandi_, Oct 20 2013