7. From the set $A=\{1,2, \cdots, 30\}$, select five different numbers such that these five numbers form an arithmetic sequence. The number of different arithmetic sequences obtained is $\qquad$ .
7. 196.

Let the five numbers be $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}$, with a common difference of $d$.
From $a_{5}-a_{1}=4d$, we know $a_{1} \equiv a_{5}(\bmod 4)$.
Divide the set $A=\{1,2, \cdots, 30\}$ into four categories based on the remainder modulo 4:
$$
\begin{array}{l}
B=\{1,5,9, \cdots, 29\}, \\
C=\{2,6,10, \cdots, 30\}, \\
D=\{3,7,11, \cdots, 27\}, \\
E=\{4,8,12, \cdots, 28\} .
\end{array}
$$

It is easy to see that sets $B$ and $C$ each have eight elements, and sets $D$ and $E$ each have seven elements.

The key to determining a five-term arithmetic sequence is to determine the first and last terms of the sequence, i.e., to select two elements from the sets $B, C, D, E$ in any order, hence we get
$$
A_{8}^{2}+A_{8}^{2}+A_{7}^{2}+A_{7}^{2}=196
$$

different arithmetic sequences.