fcn powers(m){[0.0..].tweak(fcn(n,m){a:=n; do(m-1){a*=n} a}.fp1(m))}
var squared=powers(2), cubed=powers(3);

fcn filtered(sg,cg){s:=sg.peek(); c:=cg.peek();
   if(s==c){ cg.next(); sg.next(); return(self.fcn(sg,cg)) }
   if(s>c) { cg.next(); return(self.fcn(sg,cg)); }
   sg.next(); return(s);
}
var f=[0..].tweak(filtered.fp(squared,cubed))
f.drop(20).walk(10).println();