In a similar vein I got really hooked in school on Lychrel numbers => take a number x and reverse its digits to form y. Add x and y, repeat. Eventually this pro

In a similar vein I got really hooked in school on Lychrel numbers => take a number x and reverse its digits to form y. Add x and y, repeat. Eventually this process leads to numbers that are palindromic (they are the same if you reverse their digits). Except some numbers like 196 do not seem to ever form a palindrome. No one knows if this is true or if the palindrome is so big that computers have yet to find it.