login
A090575
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 at the center of one of the 6 faces of the combination cube.
3
1, 5, 17, 52, 164, 496, 1608, 5008, 16024, 48732, 153564, 460984, 1437632, 4263236, 13150544, 38498798, 117497284
OFFSET
0,2
COMMENTS
See A090573.
EXAMPLE
a(1)=5 because the empty space located at the center of a face of the combination cube in the assumed initial configuration can be replaced in the first move by either the cube from the center of the combination cube or by one of the 4 adjacent cubes located at the edges of the face initially containing the empty space.
PROG
(Python) # uses alst(), swap() in A089473, moves3d() in A090573
moves = lambda p, shape: moves3d(p, shape)
start, shape = "1234-56789ABCDEFGHIJKLMNOPQ", (3, 3, 3)
print(alst(start, shape, maxd=12)) # Michael S. Branicky, Dec 28 2020
CROSSREFS
A090572 2 X 2 X 2 puzzle, A090573, A090574, A090576 3 X 3 X 3 puzzle with different initial configurations.
Sequence in context: A178703 A248875 A037544 * A191139 A107167 A201478
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