Problem 060

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jnash67
Posts: 3
Joined: Wed Jun 23, 2010 11:34 pm

Re: Problem #60

Post by jnash67 »

jaap wrote:Tommy137 was pointing out exactly that - the inequalities that DiogoRegateiro was using while searching for a set of 5 primes were invalid. By using the counterexample of 5 consecutive primes (consecutive so that they are approximately the same size) he showed that four of them would certainly be larger than N/2. Hence the fourth of Diogo's inequalities does not hold in general. Also, it seems to me that N was merely some arbitrary upper bound or search limit for the answer that Diogo was using.
OK. Thx.
StephanKoehler
Posts: 1
Joined: Mon Jan 11, 2021 4:44 pm

Re: Problem 060

Post by StephanKoehler »

I just want to point out that the given solution of four primes [3, 7, 109, 673] is actually wrong. The following sequence meets the criteria and has a lower sum [7, 9, 19, 433].
Nonetheless, using the same algorithm I was able to get the correct answer for five primes.
mdean
Posts: 170
Joined: Tue Aug 02, 2011 2:05 am

Re: Problem 060

Post by mdean »

StephanKoehler wrote: Mon Jan 11, 2021 4:56 pm I just want to point out that the given solution of four primes [3, 7, 109, 673] is actually wrong. The following sequence meets the criteria and has a lower sum [7, 9, 19, 433].
Nonetheless, using the same algorithm I was able to get the correct answer for five primes.
9 is not prime
Image
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