OFFSET
0,5
COMMENTS
For a guide to related sequences, see A211795.
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,-1,-1,0,2,-1).
FORMULA
a(n) = 2*a(n-1)-a(n-3)-a(n-4)+2*a(n-6)-a(n-7).
G.f.: x^3*(3*x^2+2*x+1)/((x-1)^4*(x+1)*(x^2+x+1)). - Colin Barker, Oct 07 2012
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w == x + 2 y + 3 z - n, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A212254 *)
(* Peter J. C. Moses, Apr 13 2012 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 15 2012
STATUS
approved