Find the smallest positive integer N such that a concatenation of N and 2*N
is a pandigital number.
30729 has this feature, but it is not the smallest number.
(In reply to
All of them by Charlie)
Given base 10, Charlie's N=13485 is the smallest. Yet, by definition a number is pandigital if its significant digits have each of the digits represented for its base. And in base 2, where N = 1, 2N = 10 and N2N = 110 or, in base 10, 6  which is likely the smallest such number with bases unrestricted.
(Yes, I know, by default, if not stated, an inference is base 10 numbers  yet, I wanted to be able to give an answer that was not computed by programmed code.)

Posted by Dej Mar
on 20151219 19:30:21 