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These problems deal with sequences of numbers. Can you spot what the sequences' rules are?
Difficulty: 2 of 5 Latest: Emirps census
An emirp (prime spelled backwards) is a prime number that results in a different prime when its decimal digits are reversed.
This definition excludes the related palindromic primes.

13, 17, 31, 37, 71... are emirps.


List values of q(n) (the number of emirps of length n) for n=2 to 6.

(No Solution Yet, 2 Comments) Submitted on 2018-10-12 by Ady TZIDON   
Page 1 of 25   next >>    
Difficulty: 3 of 5Reversal creates average |
Posted on 2018-10-10 by Ady TZIDON (No Solution Yet, 7 Comments)
Difficulty: 3 of 52Z out | Rating: 5.00
Posted on 2018-10-05 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 3 of 5At least 3 zeroes |
Posted on 2018-10-03 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 2 of 5Name the sequence |
Posted on 2018-09-17 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 1 of 5What's next? (3) |
Posted on 2018-08-19 by Ady TZIDON (No Solution Yet, 3 Comments)
Difficulty: 4 of 5Just 3 digits |
Posted on 2018-05-17 by Ady TZIDON (Solution Posted, 4 Comments)
Difficulty: 2 of 5What's Seven Got To Do With It? | Rating: 3.00
Posted on 2018-05-14 by Larry (Solution Posted, 2 Comments)
Difficulty: 4 of 5How about 138? |
Posted on 2018-05-10 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 2 of 5Simple recursion |
Posted on 2018-04-08 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Prime records | Rating: 5.00
Posted on 2018-04-06 by Math Man (No Solution Yet, 3 Comments)
Difficulty: 2 of 5One square implies many |
Posted on 2018-03-28 by Ady TZIDON (No Solution Yet, 6 Comments)
Difficulty: 2 of 5Starting with 1,2,3 |
Posted on 2018-03-17 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 4 of 5Seven given - the eighth TBD |
Posted on 2018-03-14 by Ady TZIDON (Solution Posted, 6 Comments)
Difficulty: 3 of 515=5*3 |
Posted on 2018-03-01 by Ady TZIDON (Solution Posted, 1 Comments)
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