604890domain: NAppears in sequencesa(n) = [ a(n-1)/a(1) ] + [ a(n-1)/a(2) ] + ... + [ a(n-1)/a(n-1) ] for n >= 3, with initial terms 1,2.at n=18A022862If the decimal expansion of n is d_1 ... d_k, a(n) = Sum d_i!*binomial(10,d_i).at n=27A306958