I can't see how that data matches the first formula you showed. But to get the answer with this data:

Formula: copy to clipboard
=SUMPRODUCT($A$1:$A$5,6-$B$1:$B$5)/(COUNT($A$1:$A$5)*(COUNT($A$1:$A$5)+1)/2)


Also new members cannot include links, but you are allowed to attach a file. Please see my instructions above.