b3 = -18
b1 = -2
b5 = -162
b4 = -sqrt(-18*-162)= -54
bn = bn-1 * q
q = bn / bn-1 = b5 / b4 = 162 / 54 = 3
S5 = (-162 * 3 + 2) / 2 = -242
b3 = -18
b1 = -2
b5 = -162
b4 = -sqrt(-18*-162)= -54
bn = bn-1 * q
q = bn / bn-1 = b5 / b4 = 162 / 54 = 3
S5 = (-162 * 3 + 2) / 2 = -242