OFFSET
0,6
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..2000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,0,0,1,-3,3,-1).
FORMULA
G.f.: x^4*(1+x-x^2+2*x^3-x^4+x^5)/((1-x)^3*(1-x^7)).
a(2-n) = (-1)*A055610(n).
MATHEMATICA
Table[Floor[(n(n-1)(n-2))/14], {n, 0, 50}] (* or *)
LinearRecurrence[{3, -3, 1, 0, 0, 0, 1, -3, 3, -1}, {0, 0, 0, 0, 1, 4, 8, 15, 24, 36}, 50] (* Harvey P. Dale, Jan 03 2024 *)
PROG
(PARI) a(n)=n*(n-1)*(n-2)\14
(Magma) [Floor(3*Binomial(n, 3)/7): n in [0..50]]; // G. C. Greubel, Oct 16 2024
(SageMath) [3*binomial(n, 3)//7 for n in range(51)] # G. C. Greubel, Oct 16 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Additional comments from Michael Somos, Jun 02 2000.
STATUS
approved