STREAK
0d
LV 1
0 XP
Institute site
Problem Bank
· seq-4
Sequences & Series · Recognizing closed forms
AMC 10 style
●●●○○ 6/10
~4 min
⏱ 0:00
A sequence satisfies
a
1
=
1
a_1 = 1
a
1
=
1
and
a
n
=
a
n
−
1
+
2
n
−
1
a_n = a_{n-1} + 2n - 1
a
n
=
a
n
−
1
+
2
n
−
1
for
n
≥
2
n \ge 2
n
≥
2
. What is
a
15
a_{15}
a
15
?
recursion
pattern
Submit
Hint 1 of 3
Show solution
∂
Learn
Σ
Problems
⊕
Contests
↻
Review
∇
Dashboard