OFFSET
0,4
REFERENCES
Graham et al., Handbook of Combinatorics, Vol. 2, p. 1234.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Christian Meyer, On conjecture no. 76 arising from the OEIS, preprint, 2004. [cached copy]
Ralf Stephan, Prove or disprove: 100 conjectures from the OEIS, arXiv:math/0409509 [math.CO], 2004.
Eric Weisstein's World of Mathematics, Turán Graph [From Reinhard Zumkeller, Nov 30 2009]
Wikipedia, Turán graph [From Reinhard Zumkeller, Nov 30 2009]
Index entries for linear recurrences with constant coefficients, signature (2, -1, 0, 0, 0, 0, 0, 0, 1, -2, 1).
FORMULA
G.f.: x*(1/(1-x) - 1/(1-x^9))/(1-x)^2. - Ralf Stephan, Mar 05 2004
a(n) = Sum_{k=0..n} A168182(k)*(n-k). - Reinhard Zumkeller, Nov 30 2009
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
a(n) = Sum_{i=1..n} floor(8*i/9). - Wesley Ivan Hurt, Sep 12 2017
MATHEMATICA
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 *)
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 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Vincenzo Librandi, Oct 20 2013
STATUS
approved