I think that with Excel 2013 you will have to use some VBA code as shown at this link (at the bottom):

https://answers.microsoft.com/en-us/...158d67d?auth=1

and then use a formula like:

=TEXTJOIN(" ",TRUE,OFFSET($A$1,(ROW(1:1)-1)*3,,3))

(with your data as from A1 and downwards).

In office 365 Excel there is a built-in function TEXTJOIN so here you don't need the VBA code.