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 A329094 #9 Sep 11 2021 19:28:10 %S A329094 1,1,1,1,1,3,3,8,17,18,51,69,126,286,485,1180,2245,4312,7247,19559, %T A329094 41403,66454,161131,337495,710899,1286527,3069554,7100614,15046664, %U A329094 29090692,57797782,144576706,313441617,628544270,1278592587,3304149943,7192582862 %N A329094 a(n) is the number of solutions when placing the numbers 1..n in an n X n square according to the rules in the Comments section. %C A329094 Place a 1 in the upper left corner of the square. Let k be the number placed last. At each step place k+1 at a distance k vertically or horizontally from k. Solutions are counted up to mirroring in the backward diagonal. That is, all solutions have 2 to the right of 1. Obviously, n is the largest possible value since the next step will inevitably lead outside the square. %e A329094 Sample solutions: %e A329094 n=6 n=7 n=8 %e A329094 1 2 - - - - 1 2 - - - - - 1 2 - - - - 8 - %e A329094 - - - - - - 7 5 - - - - 6 - - - - - - - - %e A329094 - 3 - - - - - 3 - - - - - 5 3 - - 4 - - - %e A329094 - - - - - - - - - - - - - - - - - - - - - %e A329094 - - - - - - - - - - - - - - - - - - - - - %e A329094 6 4 - - - 5 - 4 - - - - - - - - - - - - - %e A329094 - - - - - - - - - - - - - - - %e A329094 6 - - - - - 7 - %Y A329094 Cf. A308353. %K A329094 nonn %O A329094 1,6 %A A329094 _Lars Blomberg_, Nov 04 2019