OFFSET
0,3
COMMENTS
For a guide to related sequences, see A211795.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,2,2,-1,-4,-1,2,2,0,-1).
FORMULA
a(n) = 2*a(n-2)+2*a(n-3)-a(n-4)-4*a(n-5)-a(n-6)+2*a(n-7)+2*a(n-8)-a(n-10).
G.f.: x^2*(2+5*x+7*x^2+13*x^3+12*x^4+5*x^5+x^6+x^7)/((1+x)^2*(1-x)^4*(1+x+x^2)^2). [Bruno Berselli, May 06 2012]
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[2 w + 2 x == 3 y + 3 z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212567 *)
PROG
(Maxima) makelist(coeff(taylor(x^2*(2+5*x+7*x^2+13*x^3+12*x^4+5*x^5+x^6+x^7)/((1+x)^2*(1-x)^4*(1+x+x^2)^2), x, 0, n), x, n), n, 0, 43); /* Bruno Berselli, May 06 2012 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 22 2012
STATUS
approved