Minimal Prime/Examples

Examples of Minimal Primes
$881$ is a minimal prime in base $10$ because there is no prime among the proper subsequences of the digits: $8$, $1$, $88$, $81$.

The subsequence does not have to consist of consecutive digits.

Hence $149$ is not a minimal prime in base $10$, because $19$ is prime.

However, by the definition of subsequence, the digits do have to be in the same order.

So, for example, $991$ is still a minimal prime in base $10$, even though a subset of the digits can form the shorter prime $19$ by changing the order.