Recursionhard
0:00.0

For the multiplicative recurrence an=5an1(mod11)a_n = 5a_{n-1} \pmod{11} with a0=1a_0 = 1, we have an=5n(mod11)a_n = 5^n \pmod{11}. Find the period by computing the order of 5 modulo 11 (the smallest positive kk such that 5k1(mod11)5^k \equiv 1 \pmod{11}).