OFFSET
0,4
COMMENTS
LINKS
Index entries for linear recurrences with constant coefficients, signature (5, -10, 10, -5, 1).
FORMULA
a(n)=5*a(n-1)+10*a(n-2)-10*a(n-3)+5*a(n-4)-a(n-5) for n>=9.
G.f.: (2*x^3 + 6*x^4 + 2*x^5 + 16*x^6 - 4*x^7 + 2*x^9 )/(1 - 5*x + 10*x^2 - 10*x^3 + 5*x^4 - x^5)
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[Min[Abs[w - x], Abs[x - y], Abs[y - z]] > 2, s = s + 1],
{w, 0, n}, {x, 0, n}, {y, 0, n}, {z, 0, n}]; s)]];
m = Map[t[#] &, Range[0, 40]] (* A212899 *)
m/2 (* integers *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 31 2012
STATUS
approved