181480

Appears in sequences

• Number of n X n binary matrices, symmetric under 180 degree rotation, with rows, considered as binary numbers, in nondecreasing order.at n=8A141048
• a(n) = Sum_{-n<i<n, -n<j<n, gcd{i,j}=2} (n-|i|)*(n-|j|).at n=32A331772