A Slow-Growing Sequence Defined by an Unusual Recurrence

Fokko J. van de Bult, Dion C. Gijswijt, John P. Linderman +2

The sequence starts with a(1) = 1; to extend it one writes the sequence so far as XY^k, where X and Y are strings of integers, Y is nonempty and k is as large as possible: then the…