54301domain: NAppears in sequencesMaximal sum of inverse squares of the singular values of triangular anti-Hadamard matrices of order n.at n=12A005313Expansion of 1/((1-3*x)*(1-9*x)*(1-10*x)).at n=4A018090Numbers where k-th digit from right is either 0 or k.at n=29A063013