1767263171domain: NAppears in sequencesLargest prime < n-th Catalan number.at n=16A173867a(n) = Catalan(n) - n.at n=19A246604A246604 (Catalan(n)-n) with initial terms 1,0,0,2 changed to 1,1,1,3.at n=19A289615A246604 (Catalan(n)-n) with initial terms 1,0,0,2,10 changed to 1,1,1,2,11.at n=19A289616