0,2

G.f.: (1-2x)/(1+2x+4x^2).

a(n)=Product{k=0..n, (3*cos(2*pi*(k-1)/3)/2-5/4-2*0^k)^(n-k)};

a(n) = 2^n*A061347(n+2) = -2a(n-1)-4a(n-2). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 21 2008

Apart from signs, essentially the same as A096252.

Sequence in context: A019122 A019202 A096252 this_sequence A102369 A118016 A071775

Adjacent sequences: A137714 A137715 A137716 this_sequence A137718 A137719 A137720

sign

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