>>>>
>>>>Off topic but since I think you enjoy obscure code I just wrote this (purely as a mockup):
static IEnumerable<int> GetSequence()
>>>> {
>>>> bool b = false;
>>>> int x1 = 0;
>>>> int x2 = 1;
>>>>
>>>> while (true)
>>>> {
>>>> b=!b;
>>>> yield return b ? x1 += x2 : x2 += x1;
>>>> }
>>>> ]
>>>
>>>working my way through it with a pencil
>>>
>>>1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
>>>
>>>
>>>If we number them as n0, n1, n2, n3, n4, ....
>>>
>>>then n[i] = n[i-1] + n[i-2]
>>
>>yep. Next in the series is the sum of the previous two items. It's called the Fibonacci series - but I actually got it wrong. It should be:
>>0,1,1,2,3,5,8 etc
>
>
>Take -1 as starting value for x1
>
>
> int x1 = -1;
> int x2 = 1;
>
>
>As an alternative, you can do the calculation after the yield return
Or maybe just:
int x1 = -1;
int x2 = 1;
while (true)
{
yield return x1 += x2;
yield return x2 += x1;
}