OFFSET
0,3
COMMENTS
For a guide to related sequences, see A212959.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,1,2,0,-2,-1,0,1).
FORMULA
a(n) = a(n-2)+2*a(n-3)-2*a(n-5)-a(n-6)+a(n-8).
G.f.: f(x)/g(x), where f(x)=1 + x + 2*x^2 + 5*x^3 + 5*x^4 and g(x)=(1+x)((1-x)^3)(1+x+x^2)^2.
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[2 w == Max[w, x, y] - Min[w, x, y], s = s + 1],
{w, 0, n}, {x, 0, n}, {y, 0, n}]; s)]];
Map[t[#] &, Range[0, 60]] (* A212966 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 02 2012
STATUS
approved