131971

Appears in sequences

• 2*Sum(floor(C(n,w)/w),w=1..n/2-1)+floor(C(n,n/2)/(n/2)) if n is even, otherwise 2*Sum(floor(C(n,w)/w),w=1..(n-1)/2).at n=18A085573
• Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1000-1100-0111 pattern in any orientation.at n=16A146393