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 (4,-6,3,3,-6,3,3,-6,3,3,-6,3,3,-6,3,3,-6,3,3,-6,3,3,-6,3,3,-6,4,-1).
FORMULA
G.f.: x^5*(1-x+x^2)*(2-2*x-x^2+3*x^3-2*x^4+3*x^6-3*x^7+2*x^9-x^10-x^11 +3*x^12-2*x^13-x^14+3*x^15-2*x^16+2*x^18-2*x^19+x^20)/((1-x)^4*(1+x^3+x^6)*(1+x^9+x^18)). - Peter J. C. Moses, Jun 02 2014
MATHEMATICA
Table[Floor[n(n-1)(n-2)/27], {n, 0, 80}] (* or *)
LinearRecurrence[{4, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 3, 3, -6, 4, -1}, {0, 0, 0, 0, 0, 2, 4, 7, 12, 18, 26, 36, 48, 63, 80, 101, 124, 151, 181, 215, 253, 295, 342, 393, 449, 511, 577, 650}, 81] (* Harvey P. Dale, Jun 12 2023 *)
PROG
(Magma) [Floor(2*Binomial(n, 3)/9): n in [0..80]]; // G. C. Greubel, Oct 19 2024
(SageMath) [2*binomial(n, 3)//9 for n in range(81)] # G. C. Greubel, Oct 19 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms added by G. C. Greubel, Oct 19 2024
STATUS
approved