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 A351107 #7 Feb 04 2022 14:40:23 %S A351107 1,3,23,1470,914525 %N A351107 Number of simple paths for a Racetrack car (using Moore neighborhood) with initial velocity zero, going from one corner to the diagonally opposite corner on an n X n grid. %H A351107 Wikipedia, <a href="https://en.wikipedia.org/wiki/Racetrack_(game)">Racetrack</a> %e A351107 For n = 3 the following paths exist (up to reflection in the diagonal). The numbers give the positions of the car after successive steps. %e A351107 ..2 ..3 ..3 ..3 ..4 ..4 .34 .56 456 548 678 678 %e A351107 .1. ..2 .2. .12 ..3 .23 .2. .43 32. 673 543 512 %e A351107 0.. 01. 01. 0.. 012 01. 01. 012 01. 012 012 043 %e A351107 Of these, only the first path is symmetric with respect to the diagonal, so the other 11 give rise to 2 paths each. In total, there are a(3) = 1 + 2*11 = 23 possible paths. %Y A351107 Main diagonal of A351106. %Y A351107 Cf. A140518, A351041, A351109, A351111. %K A351107 nonn,more %O A351107 1,2 %A A351107 _Pontus von Brömssen_, Feb 01 2022