## Problem 060

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you
are requested to be thoughtful in not posting anything
that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one

Don't post any spoilers
jnash67
Posts: 3
Joined: Wed Jun 23, 2010 11:34 pm

### Re: Problem #60

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

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

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