Take any natural number n. If n is even, divide it by 2 to get n / 2, if n is odd multiply it by 3 and add 1 to obtain 3n + 1. Repeat the process (which has been called "Half Or Triple Plus One", or HOTPO) indefinitely. The conjecture is that no matter what number you start with, you will always eventually reach 1.
This program generates a sequence using the above rule given the first number until the sequence reaches 1 the first time.
The other function of the program is to generate sequences with starting numbers in the given interval, noting every time an equally long or longer sequence is generated as well as each time a highest number in a sequence is higher than the previous highest.
If the program don't run on your device, it may be due to lack of memory for the hash table used to speed up the calculation of the tables.