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%I #29 Sep 13 2017 03:13:04
%S 0,0,1,3,6,10,15,21,28,36,45,55,66,77,89,102,116,131,147,164,182,201,
%T 221,242,264,286,309,333,358,384,411,439,468,498,529,561,594,627,661,
%U 696,732,769,807,846,886,927,969,1012,1056,1100,1145,1191,1238,1286
%N Number of edges in 12-partite Turán graph of order n.
%D Graham et al., Handbook of Combinatorics, Vol. 2, p. 1234.
%H Vincenzo Librandi, <a href="/A033444/b033444.txt">Table of n, a(n) for n = 0..1000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TuranGraph.html">Turán Graph</a> [_Reinhard Zumkeller_, Nov 30 2009]
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Tur%C3%A1n_graph">Turán graph</a> [_Reinhard Zumkeller_, Nov 30 2009]
%H <a href="/index/Rec#order_14">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,0,0,0,1,-2,1).
%F a(n) = Sum_{k=0..n} A168185(k)*(n-k). [_Reinhard Zumkeller_, Nov 30 2009]
%F G.f.: -x^2*(x^10+x^9+x^8+x^7+x^6+x^5+x^4+x^3+x^2+x+1)/((x-1)^3*(x+1)*(x^2-x+1)*(x^2+1)*(x^2+x+1)*(x^4-x^2+1)). [_Colin Barker_, Aug 09 2012]
%F a(n) = Sum_{i=1..n} floor(11*i/12). - _Wesley Ivan Hurt_, Sep 12 2017
%t CoefficientList[Series[- x^2 (x^10 + x^9 + x^8 + x^7 + x^6 + x^5 + x^4 + x^3 + x^2 + x + 1)/((x - 1)^3 (x + 1) (x^2 - x + 1) (x^2 + 1) (x^2 + x + 1) (x^4 - x^2 + 1)), {x, 0, 60}], x] (* _Vincenzo Librandi_, Oct 20 2013 *)
%Y Cf. A002620, A000212, A033436, A033437, A033438, A033439, A033440, A033441, A033442, A033443. [_Reinhard Zumkeller_, Nov 30 2009]
%K nonn,easy
%O 0,4
%A _N. J. A. Sloane_
%E More terms from _Vincenzo Librandi_, Oct 20 2013
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