c = [1, 1, 2] 3.upto 57 do |n| if n%2 == 0 a = b = n / 2 else a = (n+1) / 2 b = a - 1 end c[n] = c[a]*c[b] + c[a-1]*c[b-1] end c.each_with_index do |n, i| puts "#{i}, #{n}" end