6. Let bi, b2, b3, be the sequence defined by the following recurrence relation: bi2 bi-i + bi-2 for i 2 3 Prove that bn is odd for any positive integer n. 7. Let co,C1,Cbe the sequence defined by the following recurrence relation: 0.12 12 C1-29 6 ci-2 for i 2 2 Prove that c 5.3+7-2" for any nonnegative integer n