Retrieving first, second and following numerical values of multiple columns

Hey Excel Forum.

I have a list of items in column A that I have sorted in 3 different groups, as shown in the attached image. After having grouped the items, I want to combine the items in a single column without the empty cells and #N/A cells.

So looking at the picture, I want to create a new column where cell X1 will show 6, X2 will show 7, then 13, 20 etc. all the way to 49. The next number should then be the first number of Group 2, i.e 2, followed by 3 and so forth.

Is there a way to get this done.

All I have so far is

=INDEX(N2:N200;MATCH(1;INDEX(ISNUMBER(N2:N200)+0;0);0))

Which looks through Group 1 and retrieves the first value.

Any ideas how I can progress, and get the remaining values?

Hope it makes a bit of sense after all.

Edit: Added excel and JPEG files.

The "Sorted" values are found in columns N:Q. Column R is where I have tried to make one column with the sorted values.