## Problem 647

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
DeKlod
Posts: 19
Joined: Tue Aug 21, 2018 8:55 am

### Problem 647

Hello all,
I know that quite some folk have solved this one already and it doesn't look too daunting, really - except that: well I'm getting 186 and not 184 as result for F_3(100).
Is that a typo that has been missed because people have gone straight on to the grown-up stuff with Sigma_k F_k(10^3) - or should I perhaps go and study Chapter 2 of 'Basic Arithmetic for Massive Dummies'?
Any input is welcome. Cheers,
Claude
jaap
Posts: 553
Joined: Tue Mar 25, 2008 3:57 pm
Contact:

### Re: Problem 647

DeKlod wrote: Fri May 17, 2019 4:38 pm I know that quite some folk have solved this one already and it doesn't look too daunting, really - except that: well I'm getting 186 and not 184 as result for F_3(100).
It really is 184. If you want, you can send me the pairs (A,B) that make up the sum by private message (you should have only four, and remember that A, B are positive so non-zero), and I'll tell you what is wrong.
DeKlod
Posts: 19
Joined: Tue Aug 21, 2018 8:55 am

### Re: Problem 647

Thanks for your quick response, jaap.
And thanks also for the offer of a PM conversation. I won't bother you just yet as I've actually only got three pairs so clearly there's something massively wrong with my approach.
Back to the drawing board then.
Cheers,
Claude

********
EDIT 10 minutes later: Now I get 184 with 4 couples... Forgot the simplest of basic checks. Would it be Friday today by any chance?