Ok, so sadly, that was too easy to google, the original riddle starts with a 1, I tried changing it to a 5 but it was still searchable.
The answer was:
"13211321322115"
Each line is a detail of the previous line composed of 2 parts, the first part the amount and the second part which number.
So the first line is "5", the detail of that line since there is one five is "15", the detail of that new line is one 1 and one 5 so "1115" then there's an amount of three ones and one five so "3115", etc.
Anyhow, we have 5 winners, 200k each.
Tenshi (IGN Black K. Night) -> first winner
Cessy (IGN )
Vivi (IGN Ichigo)
Clemie (IGN Clemie)
Lucky Day (IGN Lucky Day)
I'm still internet-less, except at work and I can't play RO from work. So I'm sorry for the delay in the prizes.