5
52
526
52609
526098
5260982
52609821
526098212
5260982128
52609821281
526098212819
5260982128199
52609821281995
526098212819952
5260982128199526
52609821281995265
526098212819952652
5260982128199526522
52609821281995265229
52609821281995265229
last few digits of 5^(2^x) from x = 0 to 19, printed by least significant digit, as you can see they are the same after a certain amount.