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Accepted

Prime Number Snake

First, we want to take a look at the snake itself. Then, let's take a look at the grid, and see if there are some obvious features. So, let's fill those in: Then, because the snake has more white ...
• 68.2k
Accepted

Prime tree game

The answer is PROBABLY I don't have a proof yet, but experimenting with it will yield something like My strategy is Now my reasoning is that One idea to rigorously prove it is to use some result ...
• 6,402
Accepted

• 114k
Accepted

Smallest number containing the first 11 primes as sub-strings

Given the first 11 primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31 We can observe that: We'll always get 2, 3 and 7 for "free" (via other numbers, such as 23 and 17, etc), so they can be ignored ...
• 36.1k

A King's Hamiltonian Tours

One solution to part A:
• 1,231

Scrabble with prime numbers!

This is a huge question, and I think people can help each other here so I'm going to start with some initial strategy: I have set up this board: Which allows for this move: For a score of 2372 (...
• 14.8k
Accepted

Prime number snake (2)

(The earlier version of this answer contained more praise for this puzzle, sometimes comparing it to the earlier one. I only now noticed that this snake was indeed not posted by the OP of the original ...
• 68.2k
Accepted

• 1,532

Find an integer where each sum of 5 consecutive digits is prime

Improving upon Gareth's answer (the details of which I will not repeat) with consideration of ThomasL's suggestion, a solution with 12 primes is found: Two solutions with 11 primes were also found:
• 9,805
Accepted

• 3,621
Accepted

Scrabble with prime numbers!

EDIT2: My solution was already accepted, but (I assumed) far from optimal. I finally made myself a prime checking algorithm and checked the 32 numbers that allow maximum scoring for the main 'word'. ...
• 4,767
Accepted

Two equal-sized lists that produce prime sums

Computer search solution. A quick and dirty Python script then identifies... Here is the script: ...
• 1,124

A King's Hamiltonian Tours

A solution for part B:
• 27k

It's my sister's birthday

She was The decorator put
• 14.8k
Accepted

Find an integer where each sum of 5 consecutive digits is prime

New high score :P List of possible primes is 43, 41, 37, 31, 29, 23, 19, 17, 13, 11, 7, 5, 3, 2. Distances between those primes are 2, 4, 6, 2, 6, 4, 2, 4, 2, 4, 2, 2, 1. Which? The key observation:...
• 1,545

Splitting the Primes

A quick calculation first Parity argument Slightly more detail Answer
• 122k
Accepted

A prime time traveler

There are 25 primes below 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 So the question is whether we can gather 24 variants plus yourself in one ...
• 42.9k

Prime Number Snake

Partial answer, to be used as a springboard Parity The first thing to notice is that Then, of course, We notice also that Prime gaps The primes between 1 and 100 are: ...
• 114k