Sum of odd numbers
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
reply
//method 1:
function rowSumOddNumbers(n) {
return Math.pow(n, 3);
}
//method 2:
function rowSumOddNumbers(n) {
let index = (n-1)*n/2,sum=0;
for(let i=1;i<=n;i++){
sum += 2*(index+i) - 1
}
return sum;
}
