OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,2,-2,0,-1,1).
FORMULA
a(n) = a(n-1)+2*a(n-3)-2*a(n-4)-a(n-6)+a(n-7).
G.f.: (x^2)*(x + 2*x^2 + 2*x^3 + 5*x^4)/((1 - x)^3*(1 + x + x^2)^2).
MATHEMATICA
a[n_] := n^2 - Floor[2 n/3]^2
Table[a[n], {n, 0, 90}] (* A213036 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 06 2012
STATUS
approved