A090164 Number of configurations of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square at one of the 4 central squares.

1, 4, 10, 20, 38, 80, 174, 372, 762, 1540, 3072, 6196, 12356, 24516, 48179, 94356, 183432, 355330, 682250, 1301874, 2460591, 4617322, 8580175, 15815664, 28854386, 52154316, 93214030

Offset: 0

Author

Hugo Pfoertner, Nov 27 2003

Keywords

• fini
• more
• nonn

Crossrefs

Cf. A087725, A089484, A090165.

Programs

Maple

See link in A089473.

Python

# uses alst(), swap() in A089473
start, shape = "12345-6789ABCDEF", (4, 4)
print(alst(start, shape, maxd=15)) # Michael S. Branicky, Jan 02 2021

Extensions

a(16)-a(26) from Michael S. Branicky, Dec 28 2020