If the sum of the first $n$ terms of a series is $n(n + 1)$, the series is —

Question

Accepted Answer

$2 + 4 + 6 + 8 + \cdots$

Answer

$1 + 3 + 5 + 7 + \cdots$

Answer

$1 + 2 + 3 + 4 + \cdots$

Answer

$2 + 6 + 10 + 14 + \cdots$

If the sum of the first nnn terms of a series is n(n+1)n(n + 1)n(n+1), the series is —