66033domain: NAppears in sequencesa(n) = n(n+7)(n+1)(n^2+2n+12)/120.at n=21A051746Integers k such that 10^k+19 is a prime number.at n=19A108052a(n) = n*(n+1)*(3*n^2+5*n+4)/12.at n=22A176060