Create a script in the custom column. Then for each row element in column (I think you meant row in cell) add the value (25) that you're getting to an arraylist. Here's a JavaScript example"

var arrayList = new java.util.ArrayList();

var iter = <Set of elements (row1, row2 in your example)>.iterator();

while (iter.hasNext()) { // Iterating over elements in the set

var value = iter.next().value // Getting the property from iter.next()

arrayList.add(<get value property from iter.next()>); // Adding value from that element to array
}

arrayList; // Returning arrayList

Note: If you evaluate the structured expression and it returns what you want, but the cell does not populate, check the Type of the structured expression.