Reverse-and-add a number until it becomes a palindrome, or flag it as a Lychrel candidate.
Reverse-and-add takes a number, reverses its digits, and adds the two together. Repeating
this usually lands on a palindrome, a number that reads the same forwards and backwards. A number that
never seems to reach a palindrome is called a Lychrel candidate. The most famous one is
196, which has resisted for many thousands of steps without ever producing a palindrome.
Example: 56 → 56 + 65 = 121, and 121 is a palindrome, so 56 resolves in one iteration.
The values can grow very large, so this tool stops after 500 iterations and reports a candidate if no
palindrome appears by then.