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Niels Henrik Abels Math Contest (Norwegian Math Olympiad) Final Round
2024 Abelkonkurransen Finale
2a
2a
Part of
2024 Abelkonkurransen Finale
Problems
(1)
Finding smallest sequence with no prime difference
Source: Abelkonkurransen Finale 2024, Problem 2a
3/8/2024
Positive integers
a
0
<
a
1
<
⋯
<
a
n
a_0<a_1<\dots<a_n
a
0
<
a
1
<
⋯
<
a
n
, are to be chosen so that
a
j
−
a
i
a_j-a_i
a
j
−
a
i
is not a prime for any
i
,
j
i,j
i
,
j
with
0
≤
i
<
j
≤
n
0 \le i <j \le n
0
≤
i
<
j
≤
n
. For each
n
≥
1
n \ge 1
n
≥
1
, determine the smallest possible value of
a
n
a_n
a
n
.
algebra
algebra proposed
Sequence