pseudoprime: n. A backgammon prime (six consecutive occupied
points) with one point missing. This term is an esoteric pun
derived from number theory: a number that passes a certain kind of
"primality test" may be called a `pseudoprime' (all primes pass any
such test, but so do some composite numbers), and any number that
passes several is, in some sense, almost certainly prime. The hacker
backgammon usage stems from the idea that a pseudoprime is almost as
good as a prime: it will do the same job unless you are unlucky.
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