><> (fish), 72 65 4949 46 chars
1n1-:?!;' 'o2n1-:v
v1&<no'v1&no' ':<4&;!? :<
> -:?!;&3+^
Input is supplied to interpreter:
>fish.py stohr.fish -v 10
1 2 4 7 10 13 16 19 22 25
My first ><> program, suggestions appreciated.