A number whose representation contains every numerical digit from a specified alphabet. The convention must specify the base, whether zero is required, and whether repetitions are allowed. In many counting problems, “0-to-9 pandigital” means that all ten decimal numerical digits occur exactly once; other problems require only that each occur at least once.
A pandigital prime is a prime number that is also a pandigital number for a specified radix, digit alphabet and repetition convention. For example, uses each of exactly once and is prime; trial division by prime numbers at most its square root verifies the latter condition.
The digit sum supplies a useful obstruction. A decimal number using exactly once has digit sum . If this sum is divisible by and the number exceeds , the number is composite. In particular, a number using all ten decimal digits exactly once has digit sum and cannot be prime. The filter follows from the digit sum integer congruence, independently of the order in which the digits occur.
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