Bonse's inequality

In number theory, Bonse's inequality, named after H. Bonse, relates the size of a primorial to the smallest prime that does not appear in its prime factorization. It states that if p₁, ..., p_n, p_n+1 are the smallest n + 1 prime numbers and n ≥ 4, then

$p_{n}\#=p_{1}\cdots p_{n}>p_{n+1}^{2}.$

(the middle product is short-hand for the primorial $p_{n}\#$ of p_n)

References

• Uspensky, J. V.; Heaslet, M. A. (1939). Elementary Number Theory. New York: McGraw Hill. p. 87.
• Zhang, Shaohua (2009). "A new inequality involving primes". arXiv:0908.2943v1 [math.GM].