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 A195897 #19 Jun 13 2021 08:09:35 %S A195897 28,39,90,63,64,197,15,7,5,1 %N A195897 Number of ways to place a queen, a rook, a bishop, a knight and a king on an n X n chessboard such that each piece attacks the same number of unoccupied spaces. %H A195897 Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0711.html">Problem of the month July 2011</a> %e A195897 There are 64 ways to place 5 different chess pieces on an 8 X 8 chessboard with the above condition. %e A195897 An example for a 4 X 4 board is %e A195897 ...Q %e A195897 ..NK %e A195897 B... %e A195897 R... %K A195897 fini,full,nonn %O A195897 4,1 %A A195897 _Kausthub Gudipati_, Sep 25 2011