344708domain: NAppears in sequencesNumber of 3-dimensional polyominoes (or polycubes) with n cells and trivial rotational symmetry group.at n=9A066453Number of idempotent n X n 0..1 matrices of rank n-2.at n=7A224117T(n,k)=Number of idempotent n X n 0..k matrices of rank n-2.at n=35A224118