BrainTwister #36: Prime generators

Can you solve this week’s logic puzzle? Plus our quick quiz and the answer to last week’s problem

4 September 2024

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#36 Prime generators

set by Peter Rowlett

In 1772, mathematician Leonhard Euler noticed that the value of the polynomial x² + x + 41 is a prime number if you set x=0. He also spotted it is prime if x=1 and it keeps on giving primes for values of x up to 39.

If we use x² + x + 3 instead, and put x=0, we get 3. Using x=1 gives 5, but the pattern then breaks because x=2 gives 9, which isn’t prime. So, x² + x + 3 generates a sequence of two primes.

How many…

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BrainTwister #36: Prime generators

#36 Prime generators

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