a(n) is the total number of down-steps after the final up-step in all 2-Dyck paths of length 3*n (n up-steps and 2*n down-steps).

A334680

a(n) is the total number of down-steps after the final up-step in all 2-Dyck paths of length 3*n (n up-steps and 2*n down-steps).

Terms

    a(0) =0a(1) =2a(2) =9a(3) =43a(4) =218a(5) =1155a(6) =6324a(7) =35511a(8) =203412a(9) =1184040a(10) =6983925a(11) =41652468a(12) =250763464a(13) =1521935948a(14) =9301989144a(15) =57203999295a(16) =353701790376

External references