I have been sent the following ostensible formula for A025597. * f(n) = (4/81) * sum(j=1...8, k=1...8) [(-1)^(j+k)] * [sin(j*pi/9)*sin(k*pi/9)]^2 * [(1+2cos(j*pi/9))*(1+2cos(k*pi/9))-1]^n *Could someone with power tools kindly verify a few terms? * *