137952domain: NAppears in sequencesa(1) = 1, a(2) = 2, a(n+2) = 2*a(n+1) + (n + 1)*(n + 2)*a(n).at n=7A142983Number of fixed polyaboloes (or polytans) with n cells, where the orientation of two triangles sharing a hypotenuse (making up a square) matters.at n=8A390995