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 +9*x^2 +10*x^3 +6*x^4 +x^5) / ((1-x)^3*(1+x)^2*(1+x+x^2)).
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0}, (Do[If[w == Max[Abs[w - x], Abs[x - y]], s = s + 1], {w, 0, n}, {x, 0, n}, {y, 0, n}]; s)]];
Map[t[#] &, Range[0, 60]] (* A213395 *)
PROG
(PARI) a(n)=([0, 1, 0, 0, 0, 0, 0; 0, 0, 1, 0, 0, 0, 0; 0, 0, 0, 1, 0, 0, 0; 0, 0, 0, 0, 1, 0, 0; 0, 0, 0, 0, 0, 1, 0; 0, 0, 0, 0, 0, 0, 1; 1, 0, -2, -1, 1, 2, 0]^n*[1; 4; 11; 19; 31; 44; 62])[1, 1] \\ Charles R Greathouse IV, Nov 27 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 12 2012
STATUS
approved