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These problems deal with sequences of numbers. Can you spot what the sequences' rules are?
Difficulty: 3 of 5 Latest: Descriptor Sequence Rating: 4.67
The descriptor sequence is a sequence of numbers in which the digits of each number describe the preceding number. The first number is 1. This number consists of one 1, so the second number is 11 (that is, one-one). This consists of two 1's, so the third term is 21. This consists of one 2 and one 1, so the fourth term is 1211. The first six numbers in the sequence are:

1, 11, 21, 1211, 111221, 312211.

Show that no digit greater than 3 ever occurs, and that the string 333 never occurs.

(Solution Posted, 3 Comments) Submitted on 2024-06-01 by K Sengupta   
Page 1 of 29   next >>    
Difficulty: 3 of 5No Repeated Numbers #2 | Rating: 4.00
Posted on 2024-05-15 by K Sengupta (No Solution Yet, 1 Comments)
Difficulty: 2 of 5A 2024 Problem |
Posted on 2024-05-13 by K Sengupta (No Solution Yet, 1 Comments)
Difficulty: 3 of 5My criteria |
Posted on 2024-04-17 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5A formal proof required |
Posted on 2024-03-10 by Ady TZIDON (No Solution Yet, 1 Comments)
Difficulty: 3 of 5Terrific sequence 3 | Rating: 5.00
Posted on 2024-02-04 by Math Man (No Solution Yet, 4 Comments)
Difficulty: 3 of 5Tough Sequence Problem | Rating: 5.00
Posted on 2024-01-13 by K Sengupta (Solution Posted, 1 Comments)
Difficulty: 3 of 5Consecutive | Rating: 5.00
Posted on 2023-12-25 by K Sengupta (Solution Posted, 2 Comments)
Difficulty: 3 of 5Two cases |
Posted on 2023-11-10 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 2 of 5Integers only |
Posted on 2023-09-25 by Ady TZIDON (Solution Posted, 6 Comments)
Difficulty: 2 of 5Ordinary Numbers | Rating: 5.00
Posted on 2023-06-09 by Charlie (Solution Posted, 4 Comments)
Difficulty: 3 of 5OEIS in the NYT | Rating: 5.00
Posted on 2023-05-28 by Charlie (Solution Posted, 5 Comments)
Difficulty: 3 of 5Twelve |
Posted on 2023-05-17 by Ady TZIDON (No Solution Yet, 4 Comments)
Difficulty: 3 of 5Nice infinite series |
Posted on 2023-04-11 by Ady TZIDON (No Solution Yet, 3 Comments)
Difficulty: 2 of 5Factorials galore | Rating: 5.00
Posted on 2023-04-04 by Ady TZIDON (No Solution Yet, 2 Comments)
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