But it does have to be in the same order; so, for example, 991 is still a minimal prime even though a subset of the digits can form the shorter prime 19 by changing the order.
Similarly, there are exactly 32 composite numbers which have no shorter composite subsequence: There are 146 primes congruent to 1 mod 4 which have no shorter prime congruent to 1 mod 4 subsequence: There are 113 primes congruent to 3 mod 4 which have no shorter prime congruent to 3 mod 4 subsequence: Minimal primes can be generalized to other bases.
It can be shown that there are only a finite number of minimal primes in every base.
Number of minimal (probable) primes in base n are The length of the largest minimal (probable) prime in base n are Largest minimal (probable) prime in base n (written in base 10) are Number of minimal composites in base n are The length of the largest minimal composite in base n are
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