(pronounced "la-shrel") are numbers that do not become palindromic number
s through a process now dubbed the 196-algorithm
. A palindromic number is, as the name implies, a number that reads the same from left to right and from right to left, e.g., 10301. The 196-algorithm is simply the repeated addition of a number and its reverse - this is performed first on the number, then on the result, and so on, untill a palindrome is reached. For instance:
199 + 991 = 1190
1190 + 911 = 2101
2101 + 1012 = 3113
The existence of Lychrel Numbers in base 10 is, as of yet, unproved, but their existence in base 2 has been shown. Strictly, some only consider the first number in a series a Lychrel Number. If 196 is indeed a Lycherel Number, 1157 ( = 196 + 961) won’t be considered as one.
196 isn't a coincidental choice - it's the smallest number that hasn't been shown to have a series leading to a palindrome.