equation icon  + sum o o An+ = e- (p/2)ee(p/2)i(n+1- s)2-1+s- ieG(n-+-1---s-+-ie) fnn, (157) G(n + 1 + s - ie)n=- oo + oo n -1-s+ie -(p/2)i(n+1+s) -(p/2)e sum n (n-+-1-+-s---ie)n-n A - = 2 e e (- 1) (n + 1 - s + ie)nfn. (158) n= - oo