Triangle sum of odd numbers

Triangle sum of odd numbers

// 1/10/2016 (Great Question*)

Given the triangle of consecutive odd numbers:

             1
          3     5
       7     9    11
   13    15    17    19
21    23    25    27    29
...

Calculate the row sums of this triangle from the row index (starting at index 1) e.g.:

rowSumOddNumbers(1); // 1
rowSumOddNumbers(2); // 3 + 5 = 8

// 1 
// 3 5, 2*1 + 1       row 2 * 1
// 7 9 11, 2*3 + 1          row 3 * 3
// 13 15 17 19, 2*6 + 1         row 4 * 6
// 21 23 25 27 29, 2*10 + 1         row 5 * 10
// 31 33 35 37 39 41, 2*15 + 1
// 1 1-1
// 2 2-3
// 3 4-6
// 4 7-10
// 5 11-15
// 6 16-21

// 6) 15 = 1+2+3+4+5
// 5) 10 = 1+2+3+4
// 4) 6 = 1+2+3
// 3) 3=1+2
// 2) 1=1
// 1) 0

My Solution:

function addRow(n) {
    var total=0;
   for (var i=0;i<n;i++){
       total+=i
    //   console.log(total)
   }
   var firstNum=2*total+1
   
//   console.log(firstNum)
   var sum=0;
   for (j=0;j<n;j++){
       sum+=firstNum
       firstNum+=2
       console.log('in loop ', sum)
   }
   return sum
}


addRow(42)

return n*n*n