I don’t understand why my code doesn’t work.

Here is the instructions about the problem:

Given the triangle of consecutive odd numbers:

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

Calculate the sum of the numbers in the n^th row of this triangle (starting at index 1) e.g.: (Input –> Output)

1 -->  1
2 --> 3 + 5 = 8

Bellow is my code written to the PHP:

function rowSumOddNumbers($n) {
  if ($n==1){
    return 1;
  }
  
  $licznik = 0;
  
  for ($i=$n; $i>0; $i--){
    $licznik += $i;
  }
  
  $liczba = ($licznik*$n) - 1;
  $suma = 0;

  
  for ($i=$n; $i>0; $i--){
    $suma += $liczba;
    $liczba = $liczba - 2;
  }
  
  return $suma;
  
}

The testcase which broke my code was:

Failed asserting that 15210 is identical to 2197.

I don’t want to know what code will make this fine, but a clue why mine doesn’t work. Please help

I tried to calculate how my code react and it seems fine.