I'm trying to plot a sequence of values from a given column. Unfortunately, I do not want to plot every value in said column. I only want to plot every n'th value beginning at a given cell, e.g. if n=6 and the first element is in B4 then I want to plot the data in B4, B10, B16, B22,... stopping when I reach an empty cell (e.g. if B28 was empty then it would plot only B4, B10, B16 and B22).

I can do this by manually editing the source data, but once I add too many values the next time I want to add a new value I have to add in several of the previous cell numbers (they mysteriously delete themselves when the string of data gets too long!).

Also, I have another set of data on the same graph which consists of simply a constant. Previously whenever I've added a new element from the worksheet I've simply added this constant to the relevant data series (so I have a horizontal line at this constant value). But now I'm having the same problem with this data set, i.e. the string is too long and I have to retype it several times.

If anything is unclear then I can attempt to provide more detail.
Any help would be gratefully received.

Thanks in advance,