As there have been a plethora of Challenge Caches in this area but also further afield, and because I have been able to find many of them, I thought I would set one of my own. 
I like the idea that most of the challenge cache owners do themselves qualify for the challenges that they have set - which not only shows the amount of work they have put into this hobby, but also shows that the challenge is possible to achieve – this helps the reviewer decide whether the challenge falls within GC guidelines – namely that the challenge is achievable. (note :- post moratorium in 2016 new challenge cache guidelines were put in place and one of the criteria was that COs had to have qualified themselves prior to submitting their cache)
We often hear about the 11 icon challenge – this is where you are required to find caches with 11 different icons in a single day.
I have not achieved this – mainly due to the fact that one of the icons – the webcam cache - is now a rare beast and I own two of them making finding 11 icons for me a very hard task. I fret not, I managed 9 icons once and am happy with that.
What I have managed to do however, is find 10 caches for each of 11 different icons - Traditional, Multi, Mystery, Earthcache, Letterbox, Virtual, Webcam, Wherigo, Locationless, Event and Lab (2024 : this in now 10 caches for 13 icons - CITO and Community Celebration Event now included) and this is what gave me the idea for this challenge – Find X number of caches with X number of different icons.
And so … Rather than make a straight forward numbers challenge – i.e. Find 10 caches of each of 10 icons, I thought I would use the numbers theme in a slightly different way (akin to a few of my puzzle caches)
Fibonacci ….. In mathematics, the Fibonacci numbers or Fibonacci sequence are the numbers in the following integer sequence. Starting with 0 and then 1, adding them together you get 1, then adding 1 and 1 (the next two integers in the sequence) you get 2, then 1+2, 3. 2+3, 5 and so on … So the first 9 numbers in the sequence are as follows 1, 1, 2, 3, 5, 8, 13, 21, 34.
However for the purposes of this challenge the first 1 will not be included.
Using this sequence I realised I had found a certain number of caches for each icon linked to this and so comes the challenge ….
Find the following number of caches of each icon in a day – they do not all have to be found in one day but the number relevant to each icon does - i.e. 1 wherigo in a day, 2 webcams in a day, 3 earthcaches in a day etc.. ….
So the numbers required to qualify
Find 1 Wherigo in a day
Find 2 Webcam in a day
Find 3 Earthcache in a day
Find 5 Virtual in a day
Find 8 Letterbox in a day
Find 13 Puzzle / Mystery in a day
Find 21 Multis in a day
Find 34 Trads in a day
This is 87 caches in total
To clarify - The quantities for each Icon have to be found on the same day - The icons can be found on separate days
For this reason this Cache has a difficulty rating of 5* - the terrain rating is simply relating to where the cache for this challenge can be found
I do qualify for this
The standard rules go with this as follows :-
• They must be Groundspeak caches.
• All past finds count. (So some maybe immediately eligible !)
• YOSM only counts as one cache for the virtual section
• Finds still count even if the cache subsequently gets archived.
• You may not use your own caches unless you adopted after finding it.
• Please supply a bookmark or other form of proof, screen print of qualifying caches – or list within the log (some of the categories may be viewable on your profile so this needs to be able to be seen) - though a checker from PGC has now been created (see link below)
• No ‘Tentative’ finds – you will either qualify or you don’t and at the time of logging your ‘find’ you must qualify and you must be able to demonstrate that you do qualify – though the log can be signed if you haven’t qualified this must be a ‘Write Note’ until you do qualify (qualifying is on the date you achieve the target NOT the date you signed the log – if you had already signed the log you do not need to re-visit the cache)
• Found logs that don't qualify will be deleted
The cache itself is a medium sized container (though not your usual lock and lock) with room for small TB's / coins hidden just off the path in the woods near Ightham Mote
*** Please Note : A correct checker on Project GC has now been created - Many thanks to Vogelbird ***
Good luck 
CONGRATULATIONS TO BaSHful IN COMPLETING THIS CHALLENGE AND GETTING FTF
Note :- to some purists you will see that the qualifying list does not fit the Fibonacci series correctly - as mentioned earlier the sequence goes - 1, 1, 2, 3, 5, 8, 13, 21, 34 - however for this challenge I have missed out the first '1'.
Thus - 1, 2, 3, 5, 8, 13, 21, 34
This was because when this was first submitted there was a clamp down on icon challenges and they were limited to only 8 and my original submission had 9 which included the first '1' - which was 1 event (see background image as this was created prior to having to amend)
In order to get this published I had to limit the challenge to 8 icons.
However - if you wish to be true to the Fibonacci sequence - please add 1 event to your list 
- this is optional and if you don't, you will not fail the challenge if everything else has been achieved.
If you cannot find a cache, do not assume it missing and do not put a throwdown as a replacement. ALL maintenance is the responsibility of the CO – if any is required, please add a ‘Needs Maintenance’ log to highlight the issue. Please replace all caches exactly as found