OFFSET
0,2
COMMENTS
For a guide to related sequences, see A212959.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,2,1,-1,-2,0,1).
FORMULA
a(n) = 2*a(n-2) + a(n-3) - a(n-4) - 2*a(n-5) + a(n-7).
G.f.: (1 + 4*x + 8*x^2 + 8*x^3 + 6*x^4 + 2*x^5)/((1 - x)^3 (1 + x)^2 (1 + x + x^2)).
a(n) = (n+1)^3 - A213499(n).
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w == Min[Abs[w - x], Abs[x - y]], s = s + 1],
{w, 0, n}, {x, 0, n}, {y, 0, n}]; s)]];
m = Map[t[#] &, Range[0, 60]]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 14 2012
STATUS
approved