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 A089473 Number of configurations of the sliding block 8-puzzle that require a minimum of n moves to be reached, starting with the empty square in one of the corners. 14
 1, 2, 4, 8, 16, 20, 39, 62, 116, 152, 286, 396, 748, 1024, 1893, 2512, 4485, 5638, 9529, 10878, 16993, 17110, 23952, 20224, 24047, 15578, 14560, 6274, 3910, 760, 221, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The sequence was first provided by Alexander Reinefeld in Table 1 of "Complete Solution of the Eight-Puzzle..." (see corresponding link in A087725) with a typo "749" instead of "748" for a(12). REFERENCES For references and links see A087725. LINKS Hugo Pfoertner, FORTRAN program to solve small sliding block puzzles. Hugo Pfoertner, Table of solution lengths of the 8-puzzle I. Kapustik, Cesta. J. Knuuttila, S. Broman and P. Ranta, n-Puzzle, in Finnish (2002). A. Reinefeld, Complete Solution of the Eight-Puzzle and the Benefit of Node Ordering in IDA*. Proc. 13th Int. Joint Conf. on Artificial Intelligence (1993), Chambery Savoi, France, pp. 248-253. Takaken, n-Puzzle Page. Takaken, No. 33 (8 puzzles). EXAMPLE From the starting configuration 123 456 78- the two final configurations requiring 31 moves are 647 ... 867 85- and 254 321 ... 3-1 PROG See link. CROSSREFS Cf. A087725 = maximum number of moves for n X n puzzle, A089474 = 8-puzzle starting with blank square at center, A089483 = 8-puzzle starting with blank square at mid-side, A089484 = solution lengths for 15-puzzle, A090031 - A090036 = other sliding block puzzles. Sequence in context: A125508 A067945 A166156 * A118021 A134162 A244484 Adjacent sequences:  A089470 A089471 A089472 * A089474 A089475 A089476 KEYWORD fini,full,nonn AUTHOR Hugo Pfoertner, Nov 19 2003 STATUS approved

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Last modified June 19 12:57 EDT 2019. Contains 324222 sequences. (Running on oeis4.)