How to select every other COLUMN

[Nastech]

trying to select every 1st / other column. 20 columns, 10 sets. want to be
able to select any 1 of 10 columns (use fixed cell $C$2 for 1-10).
selecting 1 column at a time works for the following example.

=INDEX(E49:X9,1,$C$2)

for pairs of colums:

1 E (2nd cols: F H J L... not used)
2 G (3rd col)
3 I (5th col)
4 K (7th)
5 M (9th, etc..

 

[smartin]

trying to select every 1st / other column. 20 columns, 10 sets. want to be
able to select any 1 of 10 columns (use fixed cell $C$2 for 1-10).
selecting 1 column at a time works for the following example.

=INDEX(E49:X9,1,$C$2)

for pairs of colums:

1 E (2nd cols: F H J L... not used)
2 G (3rd col)
3 I (5th col)
4 K (7th)
5 M (9th, etc..

Try something like

=INDEX(E49:X9,1,2*$C$2-1)

to select the first column of any 2-column group.