Sorry I was unclear. By "original formula", I mean the formula that generated the series you gave as an example of what you wanted to generate. I.e.:

(Series 1)
   30     29            1
  ---- + ---- + ... + ---- 
    1      2           30
[download]

From that, you said that you wanted to be able to compute the "general case for 'n', where n is the number of items in a series that looks similar to the example above I.e:

(Formula for Series 1)
    (  (n+1-k)  ) 
Sum (  -------  )  for k = (1..n);
    (     k     )
[download]

If you were computing the sum for 'n-1', wouldn't you want the sum:

(Series 2)
   29     28            1
  ---- + ---- + ... + ---- 
    1      2           29
[download]

That's not what your code generates, either. That's what I meant by 'fixing' the code -- making it consistent with which-ever series you wanted (top one for 'n' or bottom one for 'n-1'). But the program you implemented doesn't generate either series because it doesn't implement the formula to generate that series but instead, for n=30, generates the series:

(Series 3)
    1      2           30
  ---- + ---- + ... + ---- 
   29      28           0
[download]

That series is backwards from your original example, the code always divides by zero at the end the inner "for-loop", and skips the inner for-loop entirely, on the first iteration through the outer for-loop, making the sum, "$s", equal to "0". So the first time through the outer loop, you try to call $s->numerator & $s->denominator, but you've called them when $s=0 and no calculations have been done, thus the exception.

Where you wanting to discover something different? :-)

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