Abel summation formula
= Abel summation formula
{c}
{wiki=Abel's_summation_formula}
= Partial summation
{synonym}
= Summation by parts
{synonym}
Partial summation is the discrete analogue of <integration by parts>. If $A(x)=\sum_{n\leq x}a_n$ and $g$ is continuously differentiable, then
$$
\sum_{n\leq x}a_ng(n)=A(x)g(x)-\int_1^xA(t)g'(t)\,dt.
$$