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 Question from Nicole, a student: what is the rule to this sequence 3,6,12,24,48.....

We have two responses for you

Hi Nicole,

Here are two techniques that sometimes reveal the pattern in a sequence. The first is successive differences, that is you take the difference of each term from the previous term. Here is an example. Try it with your sequence.

A second technique is to take successive quotients, that is take the quotient of each term by the previous term. Try it.

Penny

A very important 'big idea' is that there are several possible sequences, in all of these cases.
There is an on-line web site where one can search (my search found 41 matches!).
The on-line source is: http://www.research.att.com/~njas/sequences/

There are reasons why ATT Research host such a site - and that would be interesting to investigate.

Given this came from a school exercise, I suspect that the first match is what the book/teacher anticipated.
They are expecting you to modify it a bit, until it is a pattern/sequence you recognize.
Taking out a common factor may do that, for you.

Walter Whiteley

Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.