import numpy as np
import matplotlib.pyplot as plt
n = np.linspace(-3, 7, 11)
x = np.array([0, 0, 0, 0, 2, 3, 1, 0, 0, 0, 0])
plt.stem(n, 3*x)
plt.xlabel('$n$')
plt.ylabel('$3x(n)$')
plt.ylim(0, 10)

plt.show()