64469domain: NAppears in sequencesSquare array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) = Sum_{j=0..n} k^j*binomial(n,j)*Catalan(j).at n=50A340968Semiprimes with only semiprime digits, each appearing at least once.at n=27A349275a(n) = Sum_{k=0..n} 4^k * binomial(n,k) * Catalan(k).at n=5A386387