N=int(input())

if N==1:
    print(0)
elif N==2:
    print(4)

elif N%2==1:

    ANS=N+(N-1)

    for i in range(2,N//2):
        ANS+=i*(N-i+2+N-i)
            
        
    ANS+=(N//2+1)*(N//2+2)

    print(ANS)

else:

    ANS=N+(N-1)

    for i in range(2,N//2):
        ANS+=i*(N-i+2+N-i)
            
        
    ANS+=(N//2)*(N//2+1+N//2+2)

    print(ANS)