Question

помогите со 2 пожалуйста

Answer 1

a(n) = n?(n+1)
a(1) = 1?·(1+1) = 1·2 = 2
a(2) = 2?·(2+1) = 4·3 = 12
a(3) = 3?·(3+1) = 9·4 = 36
a(4) = 4?·(4+1) = 16·5 = 80
a(5) = 5?·(5+1) = 25·6 = 150