Project Euler: Problem 1 (Possible refactorings and run time optimizations)

Question

I have been hearing a lot about Project Euler so I thought I solve one of the problems in C#. The problem as stated on the website is as follows:

If w

Answer 1

Here's a transliteration of my original F# solution into C#. Edited: It's basically mbeckish's solution as a loop rather than a function (and I remove the double count). I like mbeckish's better.

static int Euler1 ()
{
  int sum = 0;

  for (int i=3; i<1000; i+=3) sum+=i;
  for (int i=5; i<1000; i+=5) sum+=i;
  for (int i=15; i<1000; i+=15) sum-=i;

  return sum;
}

Here's the original:

let euler1 d0 d1 n =
  (seq {d0..d0..n}       |> Seq.sum) +
  (seq {d1..d1..n}       |> Seq.sum) -
  (seq {d0*d1..d0*d1..n} |> Seq.sum)

let result = euler1 3 5 (1000-1)