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 A090166 #21 Aug 06 2024 09:32:58
%S A090166 1,2,4,9,20,37,63,122,232,431,781,1392,2494,4442,7854,13899,24215,
%T A090166 41802,71167,119888,198363,323206,515778,811000,1248011,1885279,
%U A090166 2782396,4009722,5621354,7647872,10065800,12760413,15570786,18171606,20299876,21587248,21841159,20906905,18899357,16058335,12772603,9515217,6583181,4242753,2503873,1350268,643245,270303,92311,27116,5390,1115,86,18
%N A090166 Number of configurations of the 4 X 3 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 A090166 Data from Karlemo and Östergård.
%H A090166 Filip R. W. Karlemo and Patric R. J. Östergård, <a href="https://citeseerx.ist.psu.edu/pdf/79dcc35f3128794e0db2511583db60eab1853ae0">On Sliding Block Puzzles</a>, J. Combin. Math. Combin. Comp. 34 (2000), 97-107.
%H A090166 Takaken, <a href="http://www.ic-net.or.jp/home/takaken/nt/slide/index.html">11-Puzzle Page</a>.
%H A090166 Takaken, <a href="http://www.ic-net.or.jp/home/takaken/nt/slide/result43.txt">No. 43 (11 puzzles)</a>.
%o A090166 (Python) # alst(), moves(), swap() in A089473
%o A090166 alst("-123456789AB", (4, 3), v=True) # _Michael S. Branicky_, Dec 31 2020
%Y A090166 Cf. A087725. Index of last sequence term: A090033. Other nonsquare sliding block puzzles: A090034, A090035, A090036, A090167.
%K A090166 fini,full,nonn
%O A090166 0,2
%A A090166 _Hugo Pfoertner_, Nov 27 2003, Jul 07 2007