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%I #6 Dec 31 2020 02:12:29
%S 1,3,5,10,14,28,42,80,108,202,278,524,726,1348,1804,3283,4193,7322,
%T 8596,13930,14713,21721,19827,25132,18197,18978,9929,7359,2081,878,
%U 126,2
%N Number of configurations of the sliding block 8-puzzle that require a minimum of n moves to be reached, starting with the empty square at mid-side.
%D See A087725.
%H Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/sbpuzz33.txt">Table of solution lengths of the 8-puzzle</a>
%e Starting with
%e 1-2
%e 345
%e 678
%e the two final configurations requiring 31 moves are
%e 86- ... -86
%e 547 and 743
%e 231 ... 251
%p See link in A089473.
%o (Python) # alst(), moves(), swap() in A089473
%o print(alst("1-2345678", (3, 3))) # _Michael S. Branicky_, Dec 30 2020
%Y Cf. A089473, A089474, A089484, A087725, A090031.
%K fini,full,nonn
%O 0,2
%A _Hugo Pfoertner_, Nov 19 2003
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