353137domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumber of Dyck n-paths all of whose ascents have lengths equal to 1 (mod 9).at n=21A212389a(n) = Sum_{k=0..floor(n/2)} binomial(k+2,4*n-8*k+2).at n=40A390222Prime numbersat n=30225