OFFSET
0,3
COMMENTS
Periodic{1,1,2,2,1,1,-1,-1,-2,-2,-1,-1}.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,1,0,-1).
FORMULA
G.f.: (1-x^4)/(1-x-x^2+x^3+x^4-x^5); a(n)=cos(5*pi*n/6)/2+(1-sqrt(3)/2)sin(5*pi*n/6)+cos(pi*n/6)/2+(1+sqrt(3)/2)sin(pi*n/6);
MATHEMATICA
CoefficientList[Series[(1+x+x^2+x^3)/(1-x^2+x^4), {x, 0, 100}], x] (* or *) LinearRecurrence[{0, 1, 0, -1}, {1, 1, 2, 2}, 100] (* Harvey P. Dale, Aug 02 2015 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Feb 11 2007
STATUS
approved