Least k such that decimal representation of k*n contains only digits 0 and 4.

Terms

a(0) =4a(1) =2a(2) =148a(3) =1a(4) =8a(5) =74a(6) =572a(7) =5a(8) =49382716a(9) =4a(10) =4a(11) =37a(12) =308a(13) =286a(14) =296a(15) =25a(16) =2612a(17) =24691358a(18) =2316a(19) =2a(20) =1924a(21) =2a(22) =19148a(23) =185a(24) =16a(25) =154a(26) =163127572a(27) =143a(28) =151876a(29) =148