Here’s an interesting characterization of primes: Wilson’s Theorem. A number P is prime if and only if (P-1)! + 1...

Continue reading...# prime

## Divisibility by Seven

Everyone learns in grade school some simple tests for divisibility by small numbers such as 2, 3, 5, and 9....

Continue reading...## Formula for Primes?

Is there a nice cozy formula that will always spit out primes? Try this one: f(n) = n2 + n +...

Continue reading...## Goldbach’s Conjecture

Here’s a famous unsolved problem: is every even number greater than 2 the sum of 2 primes? The Goldbach conjecture, dating from...

Continue reading...## Largest Known Primes

Since there are infinitely many primes, what are the largest primes that we know of?The largest known primes are ones of...

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