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Nordic
2018 Nordic
2
2
Part of
2018 Nordic
Problems
(1)
Sequence contains finitely many primes
Source: Nordic Mathematical Contest 2018 Problem 2
4/10/2018
A sequence of primes
p
1
,
p
2
,
…
p_1, p_2, \dots
p
1
,
p
2
,
…
is given by two initial primes
p
1
p_1
p
1
and
p
2
p_2
p
2
, and
p
n
+
2
p_{n+2}
p
n
+
2
being the greatest prime divisor of
p
n
+
p
n
+
1
+
2018
p_n + p_{n+1} + 2018
p
n
+
p
n
+
1
+
2018
for all
n
≥
1
n \ge 1
n
≥
1
. Prove that the sequence only contains finitely many primes for all possible values of
p
1
p_1
p
1
and
p
2
p_2
p
2
.
number theory