1.NounAn infinite series in the form of
∑
n
=
0
∞
(
−
1
)
n
a
n
{\displaystyle \sum _{n=0}^{\infty }(-1)^{n}a_{n}}
or
∑
n
=
0
∞
(
−
1
)
n
+
1
a
n
{\displaystyle \sum _{n=0}^{\infty }(-1)^{n+1}a_{n}}
, where 0}">
a
n
>
0
{\displaystyle a_{n}>0}
0}"> for all
n
{\displaystyle n}
.