What is the n-th term of the sequence 2, 6, 12, 20...?

What is the n-th term of the sequence 2, 6, 12, 20...?

Answer Details

Given that 2, 6, 12, 20...? the nth term = n2 ${}^2$ + n

check: n = 1, u1 = 2

n = 2, u2 = 4 + 2 = 6

n = 3, u3 = 9 + 3 = 12

∴ n = 4, u4 = 16 + 4 = 20