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 A090576 #10 Dec 29 2020 06:33:15 %S A090576 1,4,12,40,128,412,1251,4026,12362,39624,120012,379132,1130914, %T A090576 3530916,10402781,32112656,93427431 %N A090576 Number of configurations of the 3-dimensional 3 X 3 X 3 sliding cube puzzle that require a minimum of n moves to be reached, starting with the empty space at mid-side of one of the 12 edges of the combination cube. %C A090576 See under A090573. %e A090576 a(1)=4 because the empty space located at mid-edge of one of the 12 edges of the assumed initial configuration can be replaced in the first move by any of the adjacent 2 cubes from the same edge or by the adjacent mid-face cubes of the 2 faces forming this edge. %o A090576 (Python) # uses alst(), swap() in A089473, moves3d() in A090573 %o A090576 moves = lambda p, shape: moves3d(p, shape) %o A090576 start, shape = "1-23456789ABCDEFGHIJKLMNOPQ", (3, 3, 3) %o A090576 print(alst(start, shape, maxd=12)) # _Michael S. Branicky_, Dec 28 2020 %Y A090576 Cf. A090572 2 X 2 X 2 puzzle, A090573, A090574, A090575 3 X 3 X 3 puzzle with different initial configurations. %K A090576 fini,hard,more,nonn %O A090576 0,2 %A A090576 _Hugo Pfoertner_, Jan 15 2004 %E A090576 a(13)-a(16) from _Michael S. Branicky_, Dec 28 2020