Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.
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 2401. Here positions differing by rotations or reflections are considered distinct.
Table of n, a(n) for n=0..24.
Jaap Scherphuis, Puzzle Pages
Sequence in context: A137035 A137042 A080546 * A064349 A101965 A230370
Adjacent sequences: A080551 A080552 A080553 * A080555 A080556 A080557
N. J. A. Sloane, Feb 21 2003