MathDB
Problems
Contests
National and Regional Contests
India Contests
Postal Coaching
2005 Postal Coaching
27
27
Part of
2005 Postal Coaching
Problems
(1)
A series
Source: Indian Postal Coaching 2005
10/27/2005
Let
k
k
k
be an even positive integer and define a sequence
<
x
n
>
<x_n>
<
x
n
>
by
x
1
=
1
,
x
n
+
1
=
k
x
n
+
1.
x_1= 1 , x_{n+1} = k^{x_n} +1.
x
1
=
1
,
x
n
+
1
=
k
x
n
+
1.
Show that
x
n
2
x_n ^2
x
n
2
divides
x
n
−
1
x
n
+
1
x_{n-1}x_{n+1}
x
n
−
1
x
n
+
1
for each
n
≥
2.
n \geq 2.
n
≥
2.
induction
number theory unsolved
number theory