This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A033437 Number of edges in 5-partite Turán graph of order n. 15
 0, 0, 1, 3, 6, 10, 14, 19, 25, 32, 40, 48, 57, 67, 78, 90, 102, 115, 129, 144, 160, 176, 193, 211, 230, 250, 270, 291, 313, 336, 360, 384, 409, 435, 462, 490, 518, 547, 577, 608, 640, 672, 705, 739, 774, 810, 846, 883, 921, 960, 1000, 1040, 1081, 1123, 1166, 1210, 1254 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS Apart from the initial term this is the elliptic troublemaker sequence R_n(1,5) (also sequence R_n(4,5)) in the notation of Stange (see Table 1, p. 16). For other elliptic troublemaker sequences R_n(a,b) see the cross references below. - Peter Bala, Aug 12 2013 REFERENCES R. L. Graham et al., eds., Handbook of Combinatorics, Vol. 2, p. 1234. LINKS K. E. Stange, Integral points on elliptic curves and explicit valuations of division polynomials arXiv:1108.3051 [math.NT], 2011-2014. Eric Weisstein's World of Mathematics, Turán Graph Wikipedia, Turán graph Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,1,-2,1). FORMULA G.f.: (x^5+x^4+x^3+x^2)/((1-x^5)*(1-x)^2). a(n) = Sum_{k=0..n} A011558(k)*(n-k). - Reinhard Zumkeller, Nov 30 2009 a(n) = floor( 2n^2/5 ). - Wesley Ivan Hurt, Jun 20 2013 a(n) = Sum_{i=1..n} floor(4*i/5). - Wesley Ivan Hurt, Sep 12 2017 MATHEMATICA Table[Floor[2n^2/5], {n, 0, 60}] PROG (MAGMA) [2*n^2 div 5: n in [0..60]]; // Vincenzo Librandi, Apr 20 2015 (PARI) a(n)=2*n^2\5 \\ Charles R Greathouse IV, Apr 20 2015 CROSSREFS Cf. A002620, A000212, A033436, A033438, A033439, A033440, A033441, A033442, A033443, A033444. - Reinhard Zumkeller, Nov 30 2009 Elliptic troublemaker sequences: A007590 (= R_n(2,4)), A030511 (= R_n(2,6) = R_n(4,6)), A184535 (= R_n(2,5) = R_n(3,5)). Cf. A279169. Sequence in context: A253620 A282731 A134919 * A226185 A310071 A024928 Adjacent sequences:  A033434 A033435 A033436 * A033438 A033439 A033440 KEYWORD nonn,easy AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 23 09:45 EDT 2019. Contains 328345 sequences. (Running on oeis4.)