Find the sequence whose nth term is 4n + 5 also prove that the sequence is an AP

He first five terms are
9
,
13
,
17
,
21
,
25
Explanation:
a
n
=
4
n
+
5
We can find terms
1
to
5
by substituting
n
respectively in the expression.
a
n
=
4
n
+
5
So,
a
1
=
4
⋅
(
1
)
+
5
=
9
a
2
=
4
⋅
(
2
)
+
5
=
13
a
3
=
4
⋅
(
3
)
+
5
=
17
a
4
=
4
⋅
(
4
)
+
5
=
21
a
4
=
4
⋅
(
5
)
+
5
=
25

Where is the diagram?