828193766400domain: NAppears in sequencesNumber of transitive PSL_2(ZZ) actions on a finite labeled set of size n.at n=12A121355Number of up-down runs in all permutations of {1,2,...,n}.at n=14A186371G.f.: Sum_{n>=0} (n+2)^n * x^n / (1 + (n+2)*x)^n.at n=14A229039