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A090574
Number of configurations of the 3-dimensional 3 X 3 X 3 sliding cube puzzle that require a minimum of n moves to be reached, starting with the empty space in the center of the combination cube.
3
1, 6, 24, 72, 192, 624, 2004, 6504, 19776, 62760, 186000, 583712, 1720972, 5344088, 15565416, 47816092, 137916958
OFFSET
0,2
COMMENTS
See under A090573.
EXAMPLE
a(1)=6 because the empty space in the center of the cube present in the assumed initial configuration can be replaced by any of the 6 adjacent cubes from the face centers in the first move.
PROG
(Python) # uses alst(), swap() in A089473, moves3d() in A090573
moves = lambda p, shape: moves3d(p, shape)
start, shape = "123456789ABCD-EFGHIJKLMNOPQ", (3, 3, 3)
print(alst(start, shape, maxd=12)) # Michael S. Branicky, Dec 28 2020
CROSSREFS
A090572 2 X 2 X 2 puzzle, A090573, A090575, A090576 3 X 3 X 3 puzzle with different initial configurations.
Sequence in context: A052749 A337021 A262445 * A375196 A294842 A290132
KEYWORD
fini,hard,more,nonn
AUTHOR
Hugo Pfoertner, Jan 15 2004
EXTENSIONS
a(13)-a(16) from Michael S. Branicky, Dec 28 2020
STATUS
approved