41015625domain: NAppears in sequencesa(n) = Sum_{k=0..n} (k+1) * T(n,k), with T given by A026374.at n=19A026950a(n) = Sum_{k=0..n} (k+1) * T(n,k), with T given by A026386.at n=19A026955Hypotenuses for which there exist exactly 9 distinct integer triangles.at n=14A290500