N = gets.to_i

if N == 1
  puts 0
  exit
end

if N.even?
  puts (N ** 3 + 3 * (N ** 2) + 5 * N - 6) / 6
else
  puts (N ** 3 + 3 * (N ** 2) + 5 * N - 3) / 6
end