OFFSET
0,6
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,1,-3,3,-1).
FORMULA
From R. J. Mathar, Apr 15 2010:
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-5) - 3*a(n-6) + 3*a(n-7) - a(n-8).
G.f.: x^4*(1+x-x^2+x^3) / ( (1-x)^4*(1+x+x^2+x^3+x^4) ). (End)
MATHEMATICA
CoefficientList[Series[x^4(1+x-x^2+x^3)/((1-x)^3*(1-x^5)), {x, 0, 45}], x] (* Harvey P. Dale, Feb 25 2011 *)
Floor[2*Binomial[Range[0, 50], 3]/5] (* G. C. Greubel, Oct 16 2024 *)
PROG
(Magma) [Floor(n*(n-1)*(n-2)/15): n in [0..50]]; // Vincenzo Librandi, Jul 07 2012
(SageMath) [2*binomial(n, 3)//5 for n in range(51)] # G. C. Greubel, Oct 16 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved