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 A033441 #48 Aug 11 2025 10:56:38
%S A033441 0,0,1,3,6,10,15,21,28,36,44,53,63,74,86,99,113,128,144,160,177,195,
%T A033441 214,234,255,277,300,324,348,373,399,426,454,483,513,544,576,608,641,
%U A033441 675,710,746,783,821,860,900,940,981,1023,1066,1110,1155,1201,1248,1296
%N A033441 Number of edges in 9-partite Turán graph of order n.
%D A033441 Graham et al., Handbook of Combinatorics, Vol. 2, p. 1234.
%H A033441 Vincenzo Librandi, <a href="/A033441/b033441.txt">Table of n, a(n) for n = 0..1000</a>
%H A033441 Christian Meyer, <a href="/A033441/a033441.pdf">On conjecture no. 76 arising from the OEIS</a>, preprint, 2004. [cached copy]
%H A033441 Ralf Stephan, <a href="https://arxiv.org/abs/math/0409509">Prove or disprove: 100 conjectures from the OEIS</a>, arXiv:math/0409509 [math.CO], 2004.
%H A033441 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TuranGraph.html">Turán Graph</a> [From _Reinhard Zumkeller_, Nov 30 2009]
%H A033441 Wikipedia, <a href="http://en.wikipedia.org/wiki/Tur%C3%A1n_graph">Turán graph</a> [From _Reinhard Zumkeller_, Nov 30 2009]
%H A033441 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,1,-2,1).
%F A033441 G.f.: x*(1/(1-x) - 1/(1-x^9))/(1-x)^2. - _Ralf Stephan_, Mar 05 2004
%F A033441 a(n) = Sum_{k=0..n} A168182(k)*(n-k). - _Reinhard Zumkeller_, Nov 30 2009
%F A033441 G.f.: -x^2*(x+1)*(x^2+1)*(x^4+1)/((x-1)^3*(x^2+x+1)*(x^6+x^3+1)). - _Colin Barker_, Aug 09 2012
%F A033441 a(n) = Sum_{i=1..n} floor(8*i/9). - _Wesley Ivan Hurt_, Sep 12 2017
%t A033441 CoefficientList[Series[- x^2 (x + 1) (x^2 + 1) (x^4 + 1)/((x - 1)^3 (x^2 + x + 1) (x^6 + x^3 + 1)), {x, 0, 50}], x] (* _Vincenzo Librandi_, Oct 20 2013 *)
%t A033441 LinearRecurrence[{2, -1, 0, 0, 0, 0, 0, 0, 1, -2, 1},{0, 0, 1, 3, 6, 10, 15, 21, 28, 36, 44},55] (* _Ray Chandler_, Aug 04 2015 *)
%Y A033441 Cf. A002620, A000212, A033436 - A033444. - _Reinhard Zumkeller_, Nov 30 2009
%K A033441 nonn,easy
%O A033441 0,4
%A A033441 _N. J. A. Sloane_
%E A033441 More terms from _Vincenzo Librandi_, Oct 20 2013