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 A236690 #41 Feb 16 2025 08:33:21 %S A236690 1,64,10305,12029640,115066382913,9913814758253424, %T A236690 7908201732771623795865,59973177127583169531861733624, %U A236690 4374964523946648320195747609012311225,3101392210136336400751621092299022481429113152 %N A236690 Number of simple directed paths on an n X n king graph. %C A236690 This is the number (assuming each character is unique) of strings that are possible in an n X n Boggle grid. %C A236690 This sequence gives the number of directed paths. Paths may start and end on any vertex and may be of any length. Paths of length zero are counted here. - _Andrew Howroyd_, May 12 2017 %H A236690 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/KingGraph.html">King Graph</a> %F A236690 a(n) = 2*A288033(n) + n^2. - _Andrew Howroyd_, Jun 10 2017 %Y A236690 Cf. A236753 for a simpler version of the problem without diagonal edges. %Y A236690 Cf. A288033, A140518, A158651. %K A236690 nonn,hard %O A236690 1,2 %A A236690 _Jaimal Ichharam_, Jan 30 2014 %E A236690 a(5) from _Jaimal Ichharam_, Feb 12 2014 %E A236690 Named edited and a(6)-a(10) from _Andrew Howroyd_, May 12 2017