2944414domain: NAppears in sequencesNumber of monosubstituted alkanes C(n-1)H(2n-1)-X with n-1 carbon atoms that are stereoisomers.at n=17A000620a(n) = if n mod 2 = 1 then n^3*(n-1)^2/2 else n^5/2.at n=23A122658