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 A011915 a(n) = floor(n(n-1)(n-2)(n-3)/5). 1
 0, 0, 0, 0, 4, 24, 72, 168, 336, 604, 1008, 1584, 2376, 3432, 4804, 6552, 8736, 11424, 14688, 18604, 23256, 28728, 35112, 42504, 51004, 60720, 71760, 84240, 98280, 114004, 131544, 151032, 172608, 196416, 222604, 251328, 282744, 317016, 354312 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1, 1, -4, 6, -4, 1). FORMULA a(n) = +4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +a(n-5) -4*a(n-6) +6*a(n-7) -4*a(n-8) +a(n-9). G.f.: 4*x^4*(1+2*x+2*x^3+x^4) / ( (1-x)^5*(1+x+x^2+x^3+x^4) ). - R. J. Mathar, Apr 15 2010 MATHEMATICA Table[Floor[n(n - 1)(n - 2)(n - 3)/5], {n, 1, 60}] (* Stefan Steinerberger, Apr 10 2006 *) CoefficientList[Series[4*x^4*(1+2*x+2*x^3+x^4)/((1-x)^5*(1+x+x^2+x^3+x^4)), {x, 0, 50}], x] (* Vincenzo Librandi, Jun 19 2012 PROG (Magma) [Floor(n*(n - 1)*(n - 2)*(n - 3)/5): n in [0..45]]; // Vincenzo Librandi, Jun 19 2012 CROSSREFS Sequence in context: A364600 A181617 A261256 * A199904 A250132 A025220 Adjacent sequences: A011912 A011913 A011914 * A011916 A011917 A011918 KEYWORD nonn,easy AUTHOR N. J. A. Sloane EXTENSIONS More terms from Stefan Steinerberger, Apr 10 2006 Zero added in front by R. J. Mathar, Apr 15 2010 STATUS approved

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Last modified April 25 10:01 EDT 2024. Contains 371967 sequences. (Running on oeis4.)