749088

Appears in sequences

• Number of ways to place 2 nonattacking queens on an n X n toroidal board.at n=35A172517
• Number of length n+3 0..2 arrays with no four elements in a row with pattern aabb (possibly a=b) and new values 0..2 introduced in 0..2 order.at n=11A242543
• a(n) = n!*Sum_{m=0..floor(n/3)} 1/binomial(n-m,2*m).at n=9A358852