Hi.

If I have series of 1,2,4,7,11 on X-axis with co-ordinates 0,1,2,3,4 respectively, can I calculate the X-coordinate for any number in the series in one "generalized equation" ?

For example the number 7 in the progression series is located at x=3.

So, if given the number 11, how can it's corresponding x-coordinate be calculated using a single equation?

Thanks in advance.