0,4

a(n)=4^floor(n^2/2)*((1/2-sqrt(2)/2)*cos(3*pi*n/4)+(1/2+sqrt(2)/2)*cos(pi*n/4));

Adjacent sequences: A136574 A136575 A136576 this_sequence A136578 A136579 A136580

Sequence in context: A017570 A016744 A122609 this_sequence A001025 A144318 A067223

easy,sign

Paul Barry (pbarry(AT)wit.ie), Jan 08 2008