Least k such that decimal representation of k*n contains only digits 0 and 5.

Terms

a(0) =5a(1) =25a(2) =185a(3) =125a(4) =1a(5) =925a(6) =715a(7) =625a(8) =61728395a(9) =5a(10) =5a(11) =4625a(12) =385a(13) =3575a(14) =37a(15) =3125a(16) =3265a(17) =308641975a(18) =2895a(19) =25a(20) =2405a(21) =25a(22) =23935a(23) =23125a(24) =2a(25) =1925a(26) =203909465a(27) =17875a(28) =189845a(29) =185