OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,3,0,-3,0,1).
FORMULA
G.f.: (1-x-6x^2+x^3+x^4)/((1+x)^3(1-x)^3); a(n)=3a(n-2)-3a(n-4)+a(n-6); a(n)=-(n^2+3n-1)/4-(n^2+n-3)(-1)^n/4.
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Jul 20 2005
STATUS
approved