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