OFFSET
0,3
FORMULA
a(n)=((1/2-sqrt(2)/4)*(cos(3*pi*n/4)+sin(3*pi*n/4))+(1/2+sqrt(2)/4)*(cos(3*pi*n/4)-sin(3*pi*n/4)))*9^floor((n+1)^2/8).
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Mar 07 2010
STATUS
approved