152546domain: NAppears in sequencesNumber of Dyck paths of semilength n such that at least one positive level has no peaks.at n=12A288539Number of permutations of [n] that avoid the shuffle pattern s-k-t, where s = 12 and t = 12.at n=9A324133Expansion of Product_{k>=1} (1 + x^sigma(k)) / (1 - x^sigma(k)).at n=45A333045