The Summation() function adds the body results over all i values. The syntax is:
Summation( initialization, limitvalue, body );
s = Summation( i = 1, 10, i );
s =
Sets the s variable to the value of the function.
Summation(
Begins the Summation() loop.
	i = 1,
Sets i to 1.
	10,
	i
All values of i from 1 to 10 are added together, resulting in 55.
);
This behavior is similar to Σ in the Formula Editor. The following expression:
Summation( i = 1, N Row(), x ^ 2 );

Help created on 7/12/2018