Arithmetic Sequence Sum

Arithmetic Sequence Sum

// 12/22/2015
// In Your class You have started lessons about Arithmetic Progression. 
// Because You are also a programmer, You have decided to write 
// a function arithmetic_sequence_sum(a, r, n), that will print 
// SUM of the first n elementh of the sequence with the given 
// constant r and first elementh a

// For example arithmetic_sequence_sum(2, 3, 5)

// Should return: 40

// My Solution:

function ArithmeticSequenceSum(a, r, n) {
    var total=0;
  for (var i=0; i<n; i++){
      total+=a+i*r
  }
  return total;
}

 ArithmeticSequenceSum(2,3,5)
 
 
// Test.assertEquals(ArithmeticSequenceSum(3, 2, 20), 440);
// Test.assertEquals(ArithmeticSequenceSum(2, 2, 10), 110);
// Test.assertEquals(ArithmeticSequenceSum(1, -2, 10), -80);