OFFSET
0,2
COMMENTS
See under A090577.
EXAMPLE
a(1)=4 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 one of the 4 adjacent cubes located at the edges of the face initially containing the empty space. The cube at the center of the combination cube cannot replace the empty space because the construction of this puzzle inhibits the movement of the central cube.
PROG
moves = lambda p, shape: moves3d(p, shape, fixed=13)
start, shape = "1234-56789ABCDEFGHIJKLMNOPQ", (3, 3, 3)
print(alst(start, shape, maxd=13)) # Michael S. Branicky, Dec 28 2020
CROSSREFS
KEYWORD
fini,hard,more,nonn
AUTHOR
Hugo Pfoertner, Jan 19 2004
EXTENSIONS
a(14)-a(18) from Michael S. Branicky, Dec 28 2020
STATUS
approved