OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,-3,2,-1).
FORMULA
G.f.: (1+4x^2-x^3)/((1-x+x^2))^2;
a(n) = (1-2n)*cos(Pi*n/3)+(2n+3)*sin(Pi*n/3)/sqrt(3).
MATHEMATICA
LinearRecurrence[{2, -3, 2, -1}, {1, 2, 5, 5}, 70] (* Harvey P. Dale, Nov 24 2017 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Barry, Mar 08 2011
STATUS
approved