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A089474 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 the center.

%I A089474 #6 Dec 31 2020 02:12:21
%S A089474 1,4,8,8,16,32,60,72,136,200,376,512,964,1296,2368,3084,5482,6736,
%T A089474 11132,12208,18612,18444,24968,19632,22289,13600,11842,4340,2398,472,
%U A089474 148
%N A089474 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 the center.
%D A089474 See A087725.
%H A089474 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/sbpuzz33.txt">Table of solution lengths of the 8-puzzle</a>
%e A089474 Starting with
%e A089474 123
%e A089474 4-5
%e A089474 678
%e A089474 two of the 148 configurations that require the maximum of 30 moves are
%e A089474 476 ... -86
%e A089474 2-8 and 724
%e A089474 351 ... 351
%p A089474 See link in A089473.
%o A089474 (Python) # alst(), moves(), swap() in A089473
%o A089474 print(alst("1234-5678", (3, 3))) # _Michael S. Branicky_, Dec 30 2020
%Y A089474 Cf. A089473, A089483, A089484, A087725, A090031.
%K A089474 fini,full,nonn
%O A089474 0,2
%A A089474 _Hugo Pfoertner_, Nov 19 2003