Hi Juanito ,
You can do this with the matrix multiplication function MMULT.
The following vector : {1,3,4} has 1 row and 3 columns ; the vector that you want {1,0,0,3,0,0,4,0,0} has 1 row and 9 columns.
To get a 1 x 9 vector from a 1 x 3 vector , multiply the 1 x 3 vector by a 3 x 9 matrix :
=MMULT({1,3,4},{1,0,0,0,0,0,0,0,0;0,0,0,1,0,0,0,0,0;0,0,0,0,0,0,1,0,0})
will give you the 1 x 9 vector.
Narayan