A Lychrel number is a positive integer whose decimal reverse-then-add sequence never produces a palindromic number after a positive number of iterations of the 196-algorithm. Numbers for which no palindromic number has been found after finitely many iterations are candidate Lychrel numbers. The term was coined by VanLandingham in 2002 as a variation of his girlfriend Cheryl's name (W. VanLandingham, pers. comm., Jun. 9, 2005).
The first few candidate Lychrel numbers are 196, 295, 394, 493, 592, 689, 691, 788, 790, 879, 887, ... (OEIS A023108). VanLandingham's website tabulates computationally identified candidate seeds by digit length. These seed counts do not count every candidate that eventually joins a seed's sequence, and finite searches do not prove that a palindromic number can never occur.
