Is the Binomial Coefficient Test a Reliable Prime Indicator?

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SUMMARY

The discussion centers on the conjecture regarding the Binomial Coefficient Test as a prime indicator, specifically stating that for an odd integer n > 2, n is prime if and only if the binomial coefficient ${n-1 \choose \frac{n-1}{2}} \equiv \pm 1 \mod n$. It is established that while this condition holds for all prime numbers, it also applies to certain non-prime odd numbers such as 5907, 1194649, and 12327121. The validity of this conjecture remains uncertain, with ongoing inquiries into the existence of additional non-prime odd numbers that meet this criterion.

PREREQUISITES
  • Understanding of binomial coefficients and their properties
  • Familiarity with modular arithmetic
  • Knowledge of prime number theory
  • Basic concepts of conjectures in mathematics
NEXT STEPS
  • Research "Catalan pseudoprimes" for further insights into non-prime numbers satisfying the binomial condition
  • Explore the AKS primality test for a deeper understanding of prime verification
  • Study the implications of binomial coefficients in number theory
  • Investigate the properties of modular arithmetic in relation to prime testing
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Mathematicians, number theorists, and students interested in prime number testing and the properties of binomial coefficients.

RLBrown
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I was examining the AKS and discovered this conjecture.

Please prove the following true or false.
Let n be an odd integer >2

then n is prime IFF
$\left(
\begin{array}{c}
n-1 \\
\frac{n-1}{2} \\
\end{array}
\right)

\text{ $\equiv $ }
\pm 1$ mod n
 
Last edited:
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RLBrown said:
I was examining the AKS and discovered this conjecture.

Please prove the following true or false.
Let n be an odd integer >2

then n is prime IFF
$\left(
\begin{array}{c}
n-1 \\
\frac{n-1}{2} \\
\end{array}
\right)

\text{ $\equiv $ }
\pm 1$ mod n
A quick internet search indicates that this result is false, but only just! In fact, the condition $${n-1 \choose \frac{n-1}2} \equiv \pm1\!\!\! \pmod n$$ holds whenever $n$ is prime. However, it also holds for the numbers $5907$, $1194649$ and $12327121$, which are not prime. It is not known whether there are any other non-prime odd numbers that satisfy the condition.

For more information, search for "Catalan pseudoprimes".
 

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