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The Rabbit Problem Mystery Cache

Hidden : 9/25/2025
Difficulty:
2.5 out of 5
Terrain:
1.5 out of 5

Size: Size:   micro (micro)

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Geocache Description:


☀️

THE GEOCACHE IS NOT AT THE POSTED COORDINATES

It is located at N 38° 46.X, W 090° 37.Y where X and Y are solutions to the famous Rabbit Problem from 1202.
Leonardo de Pisa first proposed this problem, which is commonly known by another name.
The goal is to determine the rabbit population, in pairs, after any number of months, assuming: rabbits mate at one month old, each pair of rabbits mate monthly, and a pair of rabbits is born one month later. The rabbits never die. Ignore biology.

Start in Month One with one pair of baby rabbits. Pairs: 1
At the end of Month Two, the original pair is still there and has mated. Pairs: 1
At the end of Month Three, the first pair of baby rabbits is born, and the original pair mated again. Pairs: 2
At the end of Month Four, the second pair of baby rabbits is born, the first pair mated, and the original pair mated again. Pairs: 3
At the end of Month Five, the third pair of baby rabbits is born from the original pair, the fourth pair of baby rabbits is born from the first pair, and the second pair of baby rabbits mated. The original pair and first pair also each mate again, and will continue to do so every month. Pairs: 5

Leonardo calculated the population without the use of technology by discovering a helpful recursive formula.
Today, we are not so limited. Solve with any tool you desire.

X = the sum of the rabbit pairs at Months Two, Nine, Twelve, and Fifteen
Y = the difference in rabbit pairs between Month Sixteen and Month Ten, minus Month Three

Enjoy the park. CITO where possible.
Congratulations stevendede on FTF!

☀️

Permission granted by St. Peter's Park Ranger Jim Freeman. Rabbit Run Park is open 5am - 7pm.

Additional Hints (Decrypt)

Chmmyr: Yrbaneqb qr Cvfn'f nyvnf Svany: oynpx ovfba

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)