On Mon, 06 Aug 2012 11:59:29 +0200, Simen Kjaeraas <simen.kjaras at gmail.com> wrote: > This is what you want, isn't it? > > recurrence!((a,n)=>a[n-1]+a[n-2])(1,1).until!(a=>a>=40000)() That is, the meat of it. The full line: writeln(recurrence!((a,n)=>a[n-1]+a[n-2])(1,1).until!(a=>a>=40000)().filter!(a=>a%2==0)().reduce!((a,b)=>a+b)()) -- Simen