You are not logged in.
I got this problem with no answers.
somebody please help me. it goes like this:
What is the next number in this sequence: 1, 2, 5, 12, 1, 13, 30, 49, 1127, 1156, 1125?
help
thanx
Offline
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.
Offline
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?
Offline
i see what you mean. still having some ideas are better then nothing right?
Offline
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
Offline
i kind of thought about that, but the first two lists they just increase all the way, and the last one decrease to 1125 from 1156. another mystery.
Offline
the fifth term is really weird (1) and last term
cos other than the fifth and last term, the sequence is generally increasing
there are also a few perfect squares hidden in the sequence, eg
1, 25, 121, 49, 1156
Last edited by wcy (2005-08-04 23:43:38)
Offline
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
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!
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
Offline
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
Offline
hmm... nice wcy. i m pretty sure that the pattern you found is no coincidence. im now looking deeper through the hints you gave me. there must be more factors to determine the next number....
Offline
www.mathwizz.com
but you need a user id and pass word you can use mine
Offline
oh ok
Offline
i'm not sure if its a coincidence, but look what i just found:
the last 2 numbers of sequence is "1156, 1125" add their first 2 values, or ones, gives us 256 and 225, which turns out to be both perfect square, and in order: they are 14,15 (14^2, 15^2)
Offline
I Mean 16,15 Sorry
Offline
i dont know it was just for fun sortof
i was looking at the numbers and was adding stuff and found it. i didnt expect it to work
Offline
very reasonable if you ask me but apparently not
Offline
yeah thats waht i think
Offline
yeah, and it doesnt work
Offline
not really usually senior question are easier this one just ... dunno lack information or something. for instance, the code you found yesterday is perfectly reasonable
Offline
i know what you mean
Offline
yes, they post it tomorrow
Offline
im trying to solve it before that
do you have msn IM?
we could discuss
Offline
yup
Offline
Two little nuggets of knowledge for anyone who's interested.
1) The contest is over, so unless kylekatarn and master got IM'ing and didn't come back here, they're too late.
2) The website has a little thing called the 'rerun contest', where it chooses a random puzzle from its archive and lets you solve it for points, for people like me who come in halfway through a contest to help them catch up. That means that the answer could still be valuable to puzzlers even once the contest is over. For this reason, NO ANSWER PROVIDED.
The bonus question is, unfortunately, lost forever...
Why did the vector cross the road?
It wanted to be normal.
Offline