Schatunowsky's Theorem/Mistake

Source Work

1986: David Wells: Curious and Interesting Numbers:

The Dictionary

$30$

1997: David Wells: Curious and Interesting Numbers (2nd ed.):

The Dictionary

$30$

Mistake

$30$ is the greatest number such that all the numbers less than it and prime to it are themselves primes. The other numbers with this property are $2$, $3$, $4$, $6$, $8$, $12$, $18$ and $24$.

Correction

While all integers are coprime to $1$ (and $30$ in particular), remember that $1$ is not classified as a prime number.

The canonical exposition of this result is for $1$ to be specifically mentioned.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $30$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $30$