41870

Appears in sequences

• Number of fixed points in all 231-avoiding involutions in S_n.at n=13A059570
• Number of (4+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.at n=11A250772
• Irregular triangle read by rows: T(n,k) is the number of n X n tic-tac-toe positions (up to rotation and reflection) with k tokens (i.e., after k plays) which occur in a game (n > 0, 0 <= k <= n^2).at n=31A317575