OFFSET
0,2
COMMENTS
a(0)=1, a(2n-1)=-k^(2n-1), a(2n)=(3k-2)k^(2n-1), k=4; G.f.: (1-kx+2(k-1)kx^2)/((1-kx)(1+kx)), k=4.
LINKS
FORMULA
a(n)=3*4^n/4+7(-4)^n/4-6*0^n/4
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Dec 22 2003
STATUS
approved