# Number sequence

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### #1 anto

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Posted 13 September 2006 - 02:22 PM

Two years ago my Calculus teacher gave us a simple number sequence

1 2 4 8 15 30 50 100

and told us to find the next term. He gave us some basic hints.

1. The answer will be less than 150
2. The only "tools" needed are those of a fifth grade math student so Im guessing adding, subtracting, multyplying, dividing etc

I had forgotten about this and just remembered it. Its driving me crazy not being able to come up with the solutino, I have my teachers email so I can email him any solution we find here and hell tell us whether we have it or not.

p.s. No one has ever solved this sequence or so he says...

### #2 Jay-qu

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Posted 13 September 2006 - 10:32 PM

no one has ever solved it.. yet apparently there is an answer

I look at the sequence and see that the numbers are never more than doubled, nor less than the sum of the previous 2..

So how do we know if we come up with the solution.. I am inclined to say 100, how do you know if thats correct?

I will keep thinking about it. Are you certain its the correct sequence?

### #3 anto

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Posted 13 September 2006 - 10:37 PM

yes the sequence is correct, 100 is not the answer b/c I've guessed 100 and he told me I was wrong. Because theres more than one possible "logic" answer this is really frustratimg, but I guess I need to keep trying until I find the answer he made up.

### #4 Tormod

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Posted 14 September 2006 - 01:29 AM

p.s. No one has ever solved this sequence or so he says...

What does that imply - that the sequence has no solution or that he just made this up for fun?

### #5 anto

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Posted 14 September 2006 - 05:40 AM

oh right..sorry if I wasn't clear . He made it up and no one has been able to solve it. I apolagize for any confusion I may have caused lol

### #6 Tormod

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Posted 14 September 2006 - 07:17 AM

According to this document, the answer is 150. However I can't understand a word of it:

http://www.gszi.bme....DF/Chapter5.pdf

### #7 TheBigDog

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Posted 14 September 2006 - 07:52 AM

Two years ago my Calculus teacher gave us a simple number sequence

1 2 4 8 15 30 50 100

and told us to find the next term. He gave us some basic hints.

1. The answer will be less than 150
2. The only "tools" needed are those of a fifth grade math student so Im guessing adding, subtracting, multyplying, dividing etc

I had forgotten about this and just remembered it. Its driving me crazy not being able to come up with the solutino, I have my teachers email so I can email him any solution we find here and hell tell us whether we have it or not.

p.s. No one has ever solved this sequence or so he says...

I am having trouble finding a pattern that yeilds an answer less than 150. My guess is that the next value should be 195. My ligic is that the first four numbers double. The fifth number 15 is the sum of the first four. From there it begins doubling again. The next number would be the fifth after the doubling restarted, so summing the previous 4 numbers yeilds 195.

My guess is that a very clever teacher is using this as a way to make kids (and now adults) think about math. There is probably no real answer.

I await the Katabatak breakdown in multiple bases from my hard shelled friend If there IS a pattern, it will not elude Turtle.

Bill

ps. This was my 2000th post.
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### #8 Boerseun

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Posted 14 September 2006 - 08:20 AM

By my calculation, the answer should be 110. But nobody here will know if I'm right, so what's the point?

### #9 C1ay

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Posted 14 September 2006 - 10:49 AM

I'm guessing 190...

oops....forgot it was less than 150.

### #10 anto

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Posted 14 September 2006 - 10:50 AM

I will tell you if its 110 by tomorrow when he answers my email. Oh and big dog It doesnt double 4 more times since 50 is not two times 30. Boerseun how did you get 110 since the method is more important than the answer

### #11 anto

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Posted 14 September 2006 - 10:55 AM

Oh one more thing. Guys I know this is frustrating because we wont know wether we have an answer right away (we have to wait until he answers my email) but I really need your help, this puzzle is driving me crazy. So please guys help me. Remember the answer has to be less than 150,so 150 can't be the answer (When I guessed 150 a while ago he gave me the extra hint that it had to be less than 150).

### #12 ughaibu

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Posted 14 September 2006 - 11:01 AM

Anto: Try this site: http://www.research....njas/sequences/
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### #13 anto

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Posted 14 September 2006 - 04:32 PM

Yeah, couldn't find anything on that site either..

### #14 infamous

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Posted 14 September 2006 - 05:27 PM

.............120...............

### #15 anto

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Posted 14 September 2006 - 05:28 PM

infamous could you please explain what method you used to get 120...thanks

### #16 TheBigDog

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Posted 14 September 2006 - 05:51 PM

I will tell you if its 110 by tomorrow when he answers my email. Oh and big dog It doesnt double 4 more times since 50 is not two times 30. Boerseun how did you get 110 since the method is more important than the answer

I guess I should stop smoking crack now.

Bill

### #17 infamous

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Posted 14 September 2006 - 05:52 PM

infamous could you please explain what method you used to get 120...thanks

Just guessing my friend...............