An isolated prime is a prime number p such that neither p − 2 nor p + 2 is prime. In other words, p is not part of a twin prime pair. For example, 23 is an isolated prime since 21 and 25 are both composite.
The first few isolated primes are
- 2, 23, 37, 47, 53, 67, 79, 83, 89, 97, … (sequence A007510 in OEIS).
Read more about this topic: Twin Prime
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