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 A321534 #9 Dec 14 2018 19:50:02 %S A321534 1,1,1,1,2,21,11,74,89,18 %N A321534 a(n) gives the number of configurations of non-attacking rooks up to symmetry on an n X n chessboard such that the number of distinct directions between the rooks is given by A321531(n). %C A321534 Conjecture: a(n) = A321532(n)/8 for n >= 4. %e A321534 For n = 5, the a(5) = 2 essentially different configurations of nonattacking rooks with the maximal number of directions between them are given by the following two chessboards: %e A321534 +---+---+---+---+---+ %e A321534 5| X | | | | | %e A321534 +---+---+---+---+---+ %e A321534 4| | | X | | | %e A321534 +---+---+---+---+---+ %e A321534 3| | | | X | | %e A321534 +---+---+---+---+---+ %e A321534 2| | | | | X | %e A321534 +---+---+---+---+---+ %e A321534 1| | X | | | | %e A321534 +---+---+---+---+---+ %e A321534 A B C D E %e A321534 +---+---+---+---+---+ %e A321534 5| X | | | | | %e A321534 +---+---+---+---+---+ %e A321534 4| | | | X | | %e A321534 +---+---+---+---+---+ %e A321534 3| | | X | | | %e A321534 +---+---+---+---+---+ %e A321534 2| | | | | X | %e A321534 +---+---+---+---+---+ %e A321534 1| | X | | | | %e A321534 +---+---+---+---+---+ %e A321534 A B C D E %Y A321534 Cf. A321531, A321532. %K A321534 nonn,more %O A321534 1,5 %A A321534 _Peter Kagey_, Nov 12 2018