In this context, a number is pandigital if it contains all the 10 digits at least once.
For example, the pandigital number 1023457869 is 2-persistent, because 2⋅1023457869 = 2046915738 is pandigital as well, but not 3-persistent, because 3⋅1023457869 = 3070373607.
As R. Honsberger proves in his book More Mathematical Morsels, there exist infinite -persistent numbers for each , but there is not a -persistent number.
Among the 10-digit number the highest persistency is 4, attained for example by 1053274689. Among the 11-digit number we reach 6 (48602175913) and among 12-digits numbers 8 (702483793156).
The first -persistent numbers, with , are 1023456789, 1023456879, 1023457689, 1023457869, 1023458679, 1023458769, 1023465789, 1023465879, 1023467589, 1023467859 more terms