108966domain: NAppears in sequencesa(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=a(2)=1 and a(3)=3.at n=18A024947a(n) = 100*n^2 + 2*n.at n=32A158127Number of ways to place 2 nonattacking nightriders on an n X n board.at n=21A172141