I am trying to use the following formula but I am getting the #VALUE! error:

=SUMPRODUCT(INDIRECT("'"&F1:F4&"'!a"&3))

Cells F1 to F4 contains the names Amarillo, Advanced Med, Augusta, Bham
which represent tab names within the worksheet. There are about 20 tabs but
I only want to sum the ones that are in F1 to F4.

Am I going about this wrong? Thanks.