317/Historical Note

Historical Note on $317$

The prime nature of the repunit $R_{317}$ was discovered by Hugh Cowie Williams in $1978$.

John David Brillhart had previously mistakenly identified it as composite.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $1,111,111,111,111,111,111$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1,111,111,111,111,111,111$