Formula for duplicating a column?

[jd8386]

Hi all,

I have a column of operators

i.e
1
-1
2
0
3
-2
etc...

I need that column to be doubled or duplicated in a separate column

i.e.
1
1
-1
-1
2
2
0
0
3
3
-2
-2
etc.

Is there a way to do this other than typing every one in by hand in my "Operator double" column?

I am trying to find a way to program this formula into excel so I can see the numbers involved, and it is giving me problems.
pn[2*i] = pn[2*i -2] - (pn[i] - pn[i-1])
pn[2*i +1] = pn[2*i -1] + (pn[i] - pn[i-1])

Thanks for the help.

[zbor]

Try: =INDEX(A:A,INT((ROW(A1)-1)/2)+1)

[jd8386]

Excellent! It works. Thanks