-337425235479domain: ZAppears in sequences(n+1)^2*a(n+1) = (9n^2+9n+3)*a(n) - 27*n^2*a(n-1), with a(0) = 1 and a(1) = 3.at n=18A006077(n+1)^2*a(n+1) = -(9*n^2 + 9*n + 3)*a(n) - 27*n^2*a(n-1), with a(0) = 1 and a(1) = -3.at n=18A291898