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 A090578 #10 Dec 29 2020 06:33:30 %S A090578 1,4,10,30,74,222,546,1628,3978,11810,28658,84520,203562,596520, %T A090578 1425924,4150232,9838116,28418002,66805554 %N A090578 Number of configurations of a variant 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-edge of one of the 12 edges of the combination cube. %C A090578 See under A090577. %e A090578 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 A090578 (Python) # uses alst(), swap() in A089473, moves3d() in A090573 %o A090578 moves = lambda p, shape: moves3d(p, shape, fixed=13) %o A090578 start, shape = "1-23456789ABCDEFGHIJKLMNOPQ", (3, 3, 3) %o A090578 print(alst(start, shape, maxd=13)) # _Michael S. Branicky_, Dec 28 2020 %Y A090578 Cf. A090577, A091521 this puzzle with different initial configurations, A090572 2X2X2 puzzle, A090573 - A090576 configurations of the 3 X 3 X 3 puzzle with 26 movable blocks. %K A090578 fini,hard,more,nonn %O A090578 0,2 %A A090578 _Hugo Pfoertner_, Jan 19 2004 %E A090578 a(14)-a(18) from _Michael S. Branicky_, Dec 28 2020