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 A090164 #8 Jan 02 2021 14:57:15 %S A090164 1,4,10,20,38,80,174,372,762,1540,3072,6196,12356,24516,48179,94356, %T A090164 183432,355330,682250,1301874,2460591,4617322,8580175,15815664, %U A090164 28854386,52154316,93214030 %N A090164 Number of configurations of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square at one of the 4 central squares. %p A090164 See link in A089473. %o A090164 (Python) # uses alst(), swap() in A089473 %o A090164 start, shape = "12345-6789ABCDEF", (4, 4) %o A090164 print(alst(start, shape, maxd=15)) # _Michael S. Branicky_, Jan 02 2021 %Y A090164 Cf. A087725, A089484, A090165. %K A090164 fini,more,nonn %O A090164 0,2 %A A090164 _Hugo Pfoertner_, Nov 27 2003 %E A090164 a(16)-a(26) from _Michael S. Branicky_, Dec 28 2020