Multiple lookup and multiple results

I have multiple columns of info. I would like to perform a lookup from 2 columns and return a list of all the matches.



a................apple................1
a................peach...............2
b................apple................3
c................pear.................1
a.................apple...............20
b.................pear................17


In the above list, I want to return a list for all the a's and apple's which would be:

1
20
If possible I would like to use a formula rather than a code. Any thoughts?

Thanks