All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info
Home > Numbers > Sequences
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 2 of 25   << prev next >>    
Difficulty: 4 of 5Verify and prove |
Posted on 2017-12-10 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 4 of 5All, except two |
Posted on 2017-12-09 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 3 of 5Expose ambiguity II |
Posted on 2017-11-09 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 4 of 5A recursive game |
Posted on 2017-10-27 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 2 of 5The next five... |
Posted on 2017-09-20 by Charlie (Solution Posted, 2 Comments)
Difficulty: 2 of 5Does it continue? 1: Chord regions |
Posted on 2017-09-13 by Jer (No Solution Yet, 9 Comments)
Difficulty: 3 of 5Sans squares |
Posted on 2017-09-12 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Lots of lods | Rating: 4.67
Posted on 2017-09-10 by Ady TZIDON (No Solution Yet, 7 Comments)
Difficulty: 2 of 5Two erased numbers |
Posted on 2017-08-24 by Ady TZIDON (No Solution Yet, 5 Comments)
Difficulty: 3 of 5Sequence of Sets |
Posted on 2017-07-30 by Bractals (No Solution Yet, 0 Comments)
Difficulty: 3 of 5Guess who |
Posted on 2017-07-16 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 3 of 5Brazilian numbers | Rating: 3.00
Posted on 2017-07-15 by Ady TZIDON (Solution Posted, 4 Comments)
Difficulty: 3 of 5A madness sequence (50 digits) |
Posted on 2017-06-11 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 1 of 518 is not enough | Rating: 3.00
Posted on 2017-06-06 by Ady TZIDON (No Solution Yet, 2 Comments)
Difficulty: 3 of 5Over 18 |
Posted on 2017-03-29 by Ady TZIDON (No Solution Yet, 3 Comments)
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (1)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2018 by Animus Pactum Consulting. All rights reserved. Privacy Information