3^2 = 9
5^9 = 25
7^2 = 49
7^4 = 1
7^8 = 1
...
7^25 = 7^(16 + 8 + 1) = 1 * 1 * 7 = 7
11^2 = 21
11^4 = 41
11^(4 + 2 + 1) = 41 * 21 * 11 = 61 * 11 = 71
13^2 = 69
13^4 = 61
13^8 = 21
13^16 = 41
13^32 = 81
13^64 = 61
13^71 = 13^(64 + 4 + 2 + 1) = 61 * 61 * 69 * 13 = 21 * 69 * 13 = 49 * 13 = 37