N 3 3n 4 5n 6 21 July 8, 2019 16 32 64 128 (4 + 3n) ⋅ (3n − 2n) − (n − 1) ⋅ 5n = (45 ^ n)/(3 ^ (2n - 1) * 5 ^ (n - 2)) (63 ^ (n + 4))/(3 ^ (2n + 6) * 7 ^ (n + 5))
