I guess with the values you provided what is the answer you are looking for,
I have come up with 4 variations.
if the data is
a1: 2
a2: 2
a3: 3
a4: 0
I get any of the following, 29.81453 or 79.90307 or 2.429121 or 2.305444
if a4: is blank
I get, 29.81453 with 2 formulas, or 2.429121 with 2 formulas.
It all stems from where the ( ) are in the formula and if we evaluate for 0 being a number to use in the count or not.
=SUM(IF(ISNUMBER(A1),A1^COUNTIF(A1:A4,">0"),0),IF(ISNUMBER(A2),A2^COUNTIF(A1:A4,">0"),0),IF(ISNUMBER(A3),A3^COUNTIF(A1:A4,">0"),0), IF(ISNUMBER(A4),A4^COUNTIF(A1:A4,">0"),0))/COUNTIF(A1:A4,">0")^(1/COUNTIF(A1:A4,">0"))
=SUM(IF(ISNUMBER(A1),A1^COUNTIF(A1:A4,">=0"),0),IF(ISNUMBER(A2),A2^COUNTIF(A1:A4,">=0"),0),IF(ISNUMBER(A3),A3^COUNTIF(A1:A4,">=0"),0), IF(ISNUMBER(A4),A4^COUNTIF(A1:A4,">=0"),0))/COUNTIF(A1:A4,">=0")^(1/COUNTIF(A1:A4,">=0"))
=(SUM(IF(ISNUMBER(A1),A1^COUNTIF(A1:A4,">0"),0),IF(ISNUMBER(A2),A2^COUNTIF(A1:A4,">0"),0),IF(ISNUMBER(A3),A3^COUNTIF(A1:A4,">0"),0), IF(ISNUMBER(A4),A4^COUNTIF(A1:A4,">0"),0))/COUNTIF(A1:A4,">0"))^(1/COUNTIF(A1:A4,">0"))
=(SUM(IF(ISNUMBER(A1),A1^COUNTIF(A1:A4,">=0"),0),IF(ISNUMBER(A2),A2^COUNTIF(A1:A4,">=0"),0),IF(ISNUMBER(A3),A3^COUNTIF(A1:A4,">=0"),0), IF(ISNUMBER(A4),A4^COUNTIF(A1:A4,">=0"),0))/COUNTIF(A1:A4,">=0"))^(1/COUNTIF(A1:A4,">=0"))
The thing to remember from this is: you need to specify what to look for with a count, if the range you are counting contains formulas.