OFFSET
0,2
COMMENTS
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1).
FORMULA
a(n) = 2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-5)-2*a(n-6)-2*a(n-7)+a(n-8).
G.f.: -(1+x^2)*(x^4+10*x^2+1) / ( (1+x)^3*(x-1)^5 ).
a(n) = A212740(n+1) for n>=0.
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[Max[w, x, y, z] <= 2 Min[w, x, y, z], s = s + 1],
{w, 0, n}, {x, 0, n}, {y, 0, n}, {z, 0, n}]; s)]];
Map[t[#] &, Range[0, 40]] (* A212742 *)
LinearRecurrence[{2, 2, -6, 0, 6, -2, -2, 1}, {1, 2, 17, 32, 97, 162, 337, 512}, 40] (* Harvey P. Dale, May 14 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 26 2012
STATUS
approved