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Post Closed as "Not suitable for this site" by Andy Putman, Andrey Rekalo, Stefan Kohl♦, Daniel Moskovich, Chris Godsil
Added +1 to p1p2...pn
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Alon Amit
Alon Amit
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Hi,

I know that the answer is no, yet I dont know how to prove it wrong. Finding a counterexample is not a good solution because it is a past written exam question with no calculators allowed. The first counterexample is about 30000... Is there a, simple preferred, solution to this problem? (This is asked in a CS discrete math exam)

The original problem is from Rosen Discrete Math, and as follows:

Prove or disprove that $p_1p_2 ... p_n$$p_1p_2 ... p_n+1$ is prime for every integer n, where $p_i$ is the ith smallest prime number.

Thanks in advance.

Hi,

I know that the answer is no, yet I dont know how to prove it wrong. Finding a counterexample is not a good solution because it is a past written exam question with no calculators allowed. The first counterexample is about 30000... Is there a, simple preferred, solution to this problem? (This is asked in a CS discrete math exam)

The original problem is from Rosen Discrete Math, and as follows:

Prove or disprove that $p_1p_2 ... p_n$ is prime for every integer n, where $p_i$ is the ith smallest prime number.

Thanks in advance.

Hi,

I know that the answer is no, yet I dont know how to prove it wrong. Finding a counterexample is not a good solution because it is a past written exam question with no calculators allowed. The first counterexample is about 30000... Is there a, simple preferred, solution to this problem? (This is asked in a CS discrete math exam)

The original problem is from Rosen Discrete Math, and as follows:

Prove or disprove that $p_1p_2 ... p_n+1$ is prime for every integer n, where $p_i$ is the ith smallest prime number.

Thanks in advance.

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kolistivra
kolistivra
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Is the product of first $n$ prime numbers $+1$ another prime number?

Hi,

I know that the answer is no, yet I dont know how to prove it wrong. Finding a counterexample is not a good solution because it is a past written exam question with no calculators allowed. The first counterexample is about 30000... Is there a, simple preferred, solution to this problem? (This is asked in a CS discrete math exam)

The original problem is from Rosen Discrete Math, and as follows:

Prove or disprove that $p_1p_2 ... p_n$ is prime for every integer n, where $p_i$ is the ith smallest prime number.

Thanks in advance.