If the decimal expansion of n is d_1 ... d_k, a(n) = Sum d_i!*binomial(10,d_i).

Terms

a(0) =1a(1) =10a(2) =90a(3) =720a(4) =5040a(5) =30240a(6) =151200a(7) =604800a(8) =1814400a(9) =3628800a(10) =11a(11) =20a(12) =100a(13) =730a(14) =5050a(15) =30250a(16) =151210a(17) =604810a(18) =1814410a(19) =3628810a(20) =91a(21) =100a(22) =180a(23) =810a(24) =5130a(25) =30330a(26) =151290a(27) =604890a(28) =1814490a(29) =3628890