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,-3,1,0,0,0,1,-3,3,-1).
FORMULA
From R. J. Mathar, Apr 15 2010: (Start)
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-7) - 3*a(n-8) + 3*a(n-9) - a(n-10).
G.f.: x^4*(1-x+2*x^2-x^4+x^5) / ( (1-x)^4*(1+x+x^2+x^3+x^4+x^5+x^6) ). (End)
MATHEMATICA
CoefficientList[Series[x^4*(1-x+2*x^2-x^4+x^5)/((1-x)^3*(1-x^7)), {x, 0, 60}], x] (* Vincenzo Librandi, Jul 07 2012 *)
LinearRecurrence[{3, -3, 1, 0, 0, 0, 1, -3, 3, -1}, {0, 0, 0, 0, 1, 2, 5, 10, 16, 24}, 60] (* Harvey P. Dale, May 03 2023 *)
PROG
(Magma) [Floor(n*(n-1)*(n-2)/21): n in [0..50]]; // Vincenzo Librandi, Jul 07 2012
(SageMath) [2*binomial(n, 3)//7 for n in range(61)] # G. C. Greubel, Oct 18 2024
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
STATUS
approved