Primorial prime - Definition and Overview

A primorial prime is a number that is one less or one more than a primorial and also a prime number. The first eight primorial primes are

5, 7, 29, 31, 211, 2309, 2311, 30029

The largest known primorial primes are p₅₉₀# - 1 and p₁₃₉₁# + 1.

Reference

The article on primorials at http://mathworld.wolfram.com/Primorial.html, from Wolfram Research, the makers of Mathematica 4. Sloane's A057705 (http://www.research.att.com/projects/OEIS?Anum=A057705) lists primorial primes of the form p# + 1, while A018239 (http://www.research.att.com/projects/OEIS?Anum=A018239) lists primorial primes of the form p# - 1.