%I #52 Apr 10 2022 10:04:12
%S 0,1,0,5,8,11,14,18,22
%N a(n) is the maximum number k of queens that can be placed on an n X n chessboard such that, for each number j in 0..k1, there is a queen attacking exactly j unoccupied squares.
%C On the 6 X 6 board in the illustration (see Example), each square containing a number is occupied by a queen, and the number in that square is the number of unoccupied squares attacked by that queen. (Each square with no number is unoccupied.)
%C Solvers:
%C a(4) = 8 by Rodolfo Kurchan
%C a(5) = 11 by Gustavo PiĆ±eiro
%C a(6) = 14 by Antonio Misericordia
%C a(7) = 18 by Antonio Misericordia
%C a(8) = 22 by Giorgio Vecchi
%H Rodolfo Kurchan, <a href="https://www.puzzlefun.online/chesspuzzlefun05">Chess Puzzle Fun 5 Uneven Attacks</a>
%e Solution illustrating a(6) = 14 by Antonio Misericordia:
%e +++++++
%e  2  7   5  4  0 
%e +++++++
%e  10    6  1 
%e +++++++
%e     11  3 
%e +++++++
%e     13  8 
%e +++++++
%e       
%e +++++++
%e    12  9  
%e +++++++
%Y Cf. A186238.
%K nonn,more
%O 0,4
%A _Rodolfo Kurchan_, Mar 24 2022
