>
>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]