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.
There are two starting positions, mirror images of each other. Sequence gives total number of positions at distance n from either start.
A puzzle in the Rubik cube family. The total number of distinct positions is 19958400.
Table of n, a(n) for n=0..10.
Jaap Scherphuis, Puzzle Pages
Sequence in context: A251782 A212797 A203017 * A224293 A053065 A091707
Adjacent sequences: A079763 A079764 A079765 * A079767 A079768 A079769
N. J. A. Sloane, Feb 20 2003