4529848320domain: NAppears in sequencesa(1) = 1; a(n+1) = a(n) * k(n), where k(n) is the number of elements of {a(j)}, 1<=j<=n, which are <= n.at n=18A094590Multiply a(n) by the first digit of a(n+1) to get a(n+2). The sequence starts with a(1) = 1 and a(2) = 2.at n=35A300759