816684

Appears in sequences

• Number of symmetric singular n X n (0,1) matrices over the reals.at n=5A086906
• Square array read by ascending antidiagonals: T(n,k) = 1/n * [x^k] 1/((1 - x)*(1 - x^2))^(n*k) for n, k >= 1.at n=42A363419