Sn = a1 * (1 - q^n) / (1-q);

S16 = a1 * (1-q^16)(1-q);
S8 = a1 * (1-q^8)/(1-q);
S(last8) = S16 - S8;

S16 = 257S(last8) = 257(S16-S8)
< --- >
7S16 = 8S8
256 * a1 * (1-q^16)(1-q) = 257 * a1 * (1-q^8)/(1-q)
-->
256(1-q^16) = 257(1-q^8)
נבצע טריק אלגברה לנוחיות:
257/256 = (1-q^16)/(1-q^8)
257/256 = (1-q^8)(1+q^8)/(1-q^8) = (1+q^8)
q^8 = 1/256
q = (1/256)^(1/8) = 1/2