This is the number of positions that can be reached in n moves from the start, but which cannot be reached in fewer than n moves.
A puzzle in the Rubik cube family. The total number of distinct positions is 625. Here positions differing by rotations and reflections are considered distinct.
Table of n, a(n) for n=0..16.
Jaap Scherphuis, Puzzle Pages
Sequence in context: A137039 A137035 A137042 * A080554 A259583 A064349
Adjacent sequences: A080543 A080544 A080545 * A080547 A080548 A080549
N. J. A. Sloane, Feb 21 2003