Find a recurrence relation

In summary, the conversation discusses finding a recurrence relation for a given sequence and explores various methods for doing so. It also raises questions about what constitutes a recurrence relation and the potential complexities of finding one.
  • #1
tgt
522
2

Homework Statement


Find the recurrence relation to

1,1,2,5,12,47,...

The Attempt at a Solution


Made all sorts of attempts. I'm not experienced with these things.

Was there a site that works these things out for you?
 
Last edited:
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  • #2
Do you have more terms? It might have no elementary relation. If you have more terms, list the difference between each consecutive terms. This forms a new sequence, do the same to this sequence. Keep doing it until the difference is a constant number. If it took you n times to do it, the relation is a polynomial of degree n.
 
  • #3
What happens if there is no elementary recurrence relation? What recurrence relation might it have then?
 
  • #4
I can give you one more term in the recurrence relation,
1,1,2,5,12,47,135,...

It is most likely non elementary
 
  • #5
Why don't you post the entire question here without truncating the series? Otherwise, it'll be difficult for the posters here to figure out the answer without even having the complete question to begin with.
 
  • #6
Would it still be a recurrence relation if the relation was a function of n only? i.e a_n = f(n) where f(n) is a function of n.

What if a_n=f(n) where a_0 is in f(n)? Is a_n still a recurrence relation?
 
  • #7
Depends what f(n) is. For example if f(n) = 2^n, then yours sequence is still the recurrence relation a_0 =1 , a_n+1 = 2 a_n.
 
  • #8
Gib Z said:
Depends what f(n) is. For example if f(n) = 2^n, then yours sequence is still the recurrence relation a_0 =1 , a_n+1 = 2 a_n.

So if the question stated give any recurrence relation and I wrote down f(n)=2^n and only that , would it be full marks?
 
  • #9
No you should probably put it in the form I did for full marks.
 
  • #10
It's not in Sloane, surprisingly.
 
  • #11
maze said:
It's not in Sloane, surprisingly.

What do you mean? I don't understand.
 
  • #12
Sloane's rather comprehensive encyclopedia of integer sequences.
 

1. What is a recurrence relation?

A recurrence relation is a mathematical equation that describes a sequence of numbers or values by relating each term to one or more of the previous terms in the sequence. It is often used in computer science and mathematics to model and solve problems that involve repeated or recursive calculations.

2. Why is it important to find a recurrence relation?

Finding a recurrence relation allows us to describe and understand a sequence of values in a concise and general form. This can help us to identify patterns and relationships within the sequence, and use them to make predictions or solve problems more efficiently.

3. How do you find a recurrence relation?

The process of finding a recurrence relation involves identifying a pattern or relationship between the terms in a sequence. This can often be done by looking at the difference between consecutive terms or by examining the factors or operations involved in generating the sequence. Once a pattern is identified, it can be expressed as a mathematical equation or formula.

4. What are some common examples of recurrence relations?

Some common examples of recurrence relations include the Fibonacci sequence, the factorial sequence, and the Tower of Hanoi problem. These can be expressed in terms of their previous terms or in a recursive form, where the solution to a problem is defined in terms of smaller instances of the same problem.

5. How are recurrence relations used in real-world applications?

Recurrence relations are used in a variety of real-world applications, such as in computer algorithms, financial modeling, and population growth analysis. They can also be used to model and solve problems in physics, engineering, and other scientific fields. By finding a recurrence relation, we can better understand and predict the behavior of complex systems and phenomena.

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