MathDB
Problems
Contests
Undergraduate contests
Putnam
2015 Putnam
A2
Putnam 2015 A2
Putnam 2015 A2
Source:
December 6, 2015
Putnam
Putnam 2015
Problem Statement
Let
a
0
=
1
,
a
1
=
2
,
a_0=1,a_1=2,
a
0
=
1
,
a
1
=
2
,
and
a
n
=
4
a
n
−
1
−
a
n
−
2
a_n=4a_{n-1}-a_{n-2}
a
n
=
4
a
n
−
1
−
a
n
−
2
for
n
≥
2.
n\ge 2.
n
≥
2.
Find an odd prime factor of
a
2015
.
a_{2015}.
a
2015
.
Back to Problems
View on AoPS