Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I'm going to put in a series just to comply, but I was wondering if anyone had advice for figuring out patterns in numbers. All I hear is that some people are natural at it.

4, 6, 10, 18...

the context here is GED, so don't make answers too complicated.

Thanks

share|improve this question
10  
A standard trick is taking differences of neighboring numbers. In this case we get 2, 4, 8, which looks like the differences double each time. So the series could be $a_n = 2+2^n$. –  Henning Makholm Sep 18 '11 at 4:19
    
Can I make a comment too complicated instead? What comes next in the sequence 0, 1, 2, 720! (that's 720 factorial), ? I think I first saw this in Hofstadter's Fluid Concepts and Creative Analogies, but I'm not positive. –  Rahul Sep 18 '11 at 5:48
    
@Rahul: For $n\in\omega$ define $f_0(n)=n$ and $f_{k+1}(n)=f_k(n)!$. The $n$-th term of the sequence is then $f_n(n)$. –  Brian M. Scott Sep 18 '11 at 7:19
1  
If people cannot find the pattern, then perhaps computer can. –  Jiri Sep 18 '11 at 12:08
3  
Next in the sequence 0,1,2,720! is 4!!!!. The rule is 0,1!,2!!,3!!!... –  Angela Richardson Sep 18 '11 at 14:50
show 1 more comment

1 Answer

up vote 0 down vote accepted

Let's define recursive formula $a_n=a_{n-1}+2^{n-1}$, so the next number is $a_5=18+2^4=34$

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.