OFFSET
0,8
LINKS
Index entries for linear recurrences with constant coefficients, signature (2, -1, 0, 0, 0, 0, 0, 0, 1, -2, 1).
FORMULA
a(n) = +2*a(n-1) -a(n-2) +a(n-9) -2*a(n-10) +a(n-11). G.f.: x^5*(x^2-x+1) / ( (1-x)^3*(1+x+x^2)*(x^6+x^3+1) ). - R. J. Mathar, Apr 15 2010
a(n) = floor( (1/3) * sum_{i=1..n} floor(i/3) ). - Wesley Ivan Hurt, Jun 06 2014
MATHEMATICA
Table[Floor[n (n-1)/18], {n, 0, 70}] (* or *) LinearRecurrence[{2, -1, 0, 0, 0, 0, 0, 0, 1, -2, 1}, {0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5}, 71] (* Harvey P. Dale, Apr 25 2012 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Dec 11 1996
STATUS
approved