Primes Expressible as x^2 + n y^2 for all n from 1 to 10/Historical Note

Historical Note on Primes Expressible as $x^2 + n y^2$ for all $n$ from $1$ to $10$

Jekuthiel Ginsburg conjectured that:

The number $1201$ seems to be the smallest prime which can be expressed in the form $x^2 + n y^2$ for all values of $n$ from $1$ to $10$.

David Wells reported in his Curious and Interesting Numbers of $1986$ that this hypothesis was presented in Volume $8$ of Scripta Mathematica, but research is needed to track down the exact issue, date and page number.

In $1992$, Charles Ashbacher reported in Journal of Recreational Mathematics that the $1201$ is not in fact the smallest, but that $1009$ and $1129$ also have this property.

In his Curious and Interesting Numbers, 2nd ed. of $1997$, Wells provided the above update.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $1201$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1009$