This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A090034 #12 Dec 31 2020 02:12:39
%S A090034 1,2,3,5,6,7,10,12,12,16,23,25,28,39,44,40,29,21,18,12,6,1
%N A090034 Number of configurations of the 3 X 2 variant of Sam Loyd's 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 A090034 Data from Karlemo and Östergård. See corresponding link in A087725.
%D A090034 See A087725.
%H A090034 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/sbpnx2.txt">Solutions of small n*2 sliding block puzzles.</a>
%H A090034 Takaken, <a href="http://www.ic-net.or.jp/home/takaken/nt/slide/index.html">n-Puzzle Page</a>.
%H A090034 Takaken, <a href="http://www.ic-net.or.jp/home/takaken/nt/slide/result32.txt">No. 32 (5 puzzles)</a>.
%e A090034 Starting with
%e A090034 123
%e A090034 45-
%e A090034 the most distant configuration corresponding to a(21)=1 is
%e A090034 45-
%e A090034 123 (i.e., it takes longest just to swap the two rows).
%o A090034 See link in A089473.
%o A090034 (Python) # alst(), moves(), swap() in A089473
%o A090034 print(alst("-12345", (3, 2))) # _Michael S. Branicky_, Dec 30 2020
%Y A090034 Cf. A087725, A089473, A090033, A090035, A090036, A090163, A090167.
%K A090034 fini,full,nonn
%O A090034 0,2
%A A090034 _Hugo Pfoertner_, Nov 23 2003