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#2 2005-08-05 03:00:59
- mathsyperson
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Re: sequence
The graphing function in Excel says that the sequence doesn't have a pattern in a polynomial of an order less than 7, and it's not a linear, power or exponential function. It is possible to create a pattern to fit the sequence, but it will probably involve x^10 and be very horrible in general. The next number in the sequence would probably be a fraction as well. I can't see any obvious pattern, so I think it's probably got some obscure non-mathematical reasoning behind it. If you tell us where you got the puzzle from, we might be able to help more.
Why did the vector cross the road?
It wanted to be normal.
#3 2005-08-05 04:31:13
- master
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Re: sequence
it's from a contest online. what i posted previously was all that was to the question. the sequence looks kind of odd, so i reckon there is a "semi-mathematical" sequence behind it. do you have any suggestions what the next number can be, just any random suggestion?
#4 2005-08-05 07:30:46
- kylekatarn
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Re: sequence
depends on the type of approch you make to that data...
#6 2005-08-05 09:32:35
- MathsIsFun
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Re: sequence
Another thought (not follwed up):
1, 2, 5, 12,
1, 13, 30, 49,
1127, 1156, 1125, ????
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
#9 2005-08-05 21:46:19
- Robin
- Guest
Re: sequence
hi,
New to the forum and thought I'd add my 1pence worth.
I have been unable to find the most likely number that is required, but with sequences, there generally isnt only a single no. that is correct. Any number can be written as the next and even proof provided for it being there.
A good way of identifying sequences is to use finite differences. I at first tried this method and it failed to provide a concrete algo, *but* it did show me a pattern.
I haven't had my daily intake of coffee, so forgive any errors (Like spotting the obvious)
Finite differences work on apply subsequent differences between no.s .. Im only interested in the first interation for my example.
1, 2, 5, 12, 1, 13, 30, 49, 1127, 1156, 1125 (Original)
1 3 7 -11 12 17 19 1078 29 -31 (Difference)
Ok notice that the difference gives the answer to the next no.
Starting difference 1+2=3 +2=5+7=12+-11 = 1 etc
Now I havent looked properly, there may be a hidden pattern in the difference which points to the desired next difference (Need Coffee) but the answer can be any no.
Lets say the next sequence is 1094. This would make the difference -31.
so 1125 + -31 = 1094
Anyway, thats my thoughts, good luck and pls take a look at my post I need your help.
Robin
#10 2005-08-05 22:06:53
- ganesh
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Re: sequence
Good post, and Welcome, Robin!
Subsequent differences, yes, sometimes they do help in find the next number in sequences.
But, what you have pointed out is, I feel, not acceptable.
You have found the difference, and then added that to the previous term.
In mathematical terms, you have found the difference between 2 terms, a and b, then added the difference to a, which would have to be b!
Character is who you are when no one is looking.
#11 2005-08-05 22:13:16
- wcy
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Re: sequence
1, 2, 5, 12, 1, 13, 30, 49, 1127, 1156, 1125?
i found this pattern:
split the numbers into groups of 3, and multiply their digits together
1
2
5 (1+2²=5)
1x2=2
1
1x3=3 (2+1²=3)
3*0=0
4x9=36, 3x6=18, 1x8=8
1*1*2*7=14, 1*4=4 (0+8²=64=4(take last digit))
1*1*5*6=30, 3*0=0
1*1*2*5=10, 1*0=0
0+0²=0
hence the answer can be any 4 digit number whose digits multiply to 0 eg. 1110.
that is the only pattern i managed to find..
but i suspect that it is significant for 1156 to be a perfect square
#13 2005-08-06 11:14:33
- kylekatarn
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Re: sequence
where did you get this sequence?
I would like to visit the website you took this from
#15 2005-08-06 11:21:37
- kylekatarn
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Re: sequence
You didn't have to post you login info. The signup is free so I created an account for myself.
#17 2005-08-06 11:25:10
- kylekatarn
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Re: sequence
the website is very cool it has a lot of math contests!
#20 2005-08-06 11:35:42
- kylekatarn
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Re: sequence
how do you apply that rule involving the other numbers?
#22 2005-08-06 11:59:23
- kylekatarn
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Re: sequence
Could it be this?
We have the following data,where Z is the unknown term
1;2;5;12;1;13;30;49;1127;1156;1125;Z
Lets create groups of 4
Code:
1 1 1127 2 13 1156 5 30 1125 12 49 Z
Let's perform a subtraction
12-5-2-1=4
49-30-13-1=5
If this is the pattern the we can write
Z-1125-1156-1127=6
Z=3414
Althought 3414 doesn't look like 1127, 1156 and 1125, but does that matters? The numbers in the group {1,2,5,12} are also different.
The last term doesn't have to start with 11(...)
I think it's a simple but logic answer.
Last edited by kylekatarn (2005-08-06 12:01:09)
#24 2005-08-06 23:16:50
- kylekatarn
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Re: sequence
I'm really stuck on this...
The site's problems are more 'math-based' or 'logic-based'?
(This one seems more logic-based.)
Last edited by kylekatarn (2005-08-06 23:19:56)