cp's OEIS Frontend

A346736 Number of configurations of the 7 X 2 variant of the sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square in one of the corners.

%I A346736 #24 Aug 03 2021 12:44:31
%S A346736 1,2,3,6,11,20,37,67,117,198,329,557,942,1575,2597,4241,6724,10535,
%T A346736 16396,25515,39362,60532,92089,138969,207274,307725,453000,664240,
%U A346736 964874,1392975,1992353,2832063,3988528,5586275,7756511,10698721,14621717,19840724,26676629
%N A346736 Number of configurations of the 7 X 2 variant of the sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square in one of the corners.
%C A346736 This sequence was originally computed by Richard Korf, but the full sequence was not included in his paper. It was later re-computed by _Tomas Rokicki_.
%H A346736 Ben Whitmore, <a href="/A346736/b346736.txt">Table of n, a(n) for n = 0..108</a>
%H A346736 Richard Korf, <a href="https://www.cs.helsinki.fi/u/bmmalone/heuristic-search-fall-2013/Korf2008.pdf">Linear-time Disk-Based Implicit Graph Search</a>, Journal of the ACM 55 (2008), No. 6.
%H A346736 Tomas Rokicki, <a href="http://forum.cubeman.org/?q=node/view/238">Twenty-Four puzzle, some observations</a>, 2011.
%e A346736 Starting from the solved configuration
%e A346736   1  2  3  4  5  6  7
%e A346736   8  9 10 11 12 13
%e A346736 the unique configuration requiring 108 moves is
%e A346736   7  6 12  4  3  9  1
%e A346736     13  5 11 10  2  8
%o A346736 (Python) # alst(), moves(), swap() in A089473
%o A346736 print(alst("-123456789abcd", (7, 2), v=True)) # _Michael S. Branicky_, Jul 31 2021
%Y A346736 Cf. A090033, A090034, A090035, A090036, A090167, A089473, A089484.
%K A346736 nonn,fini,full
%O A346736 0,2
%A A346736 _Ben Whitmore_, Jul 31 2021