bn = b1 * q^(n-1)
b6 = b1 * q^5 = 2 * 3^5 = 2 * 243 = 486
b4 = b1 * q^3 = 128 * (1/64) = 2
b9 = b1 * q^8 = 16 * (-1/2)^8 = 16 * 1/256 = 1/16
bn = b1 * q^(n-1)
b6 = b1 * q^5 = 2 * 3^5 = 2 * 243 = 486
b4 = b1 * q^3 = 128 * (1/64) = 2
b9 = b1 * q^8 = 16 * (-1/2)^8 = 16 * 1/256 = 1/16