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National and Regional Contests
Netherlands Contests
Dutch BxMO/EGMO TST
2011 Dutch BxMO TST
4
4
Part of
2011 Dutch BxMO TST
Problems
(1)
a,b greatest pos. integer such 2^a | (5^n - 3^n), 2^b <= n, prove a<=b+3
Source: Dutch BxMO TST 2011 p4
8/24/2019
Let
n
≥
2
n \ge 2
n
≥
2
be an integer. Let
a
a
a
be the greatest positive integer such that
2
a
∣
5
n
−
3
n
2^a | 5^n - 3^n
2
a
∣
5
n
−
3
n
. Let
b
b
b
be the greatest positive integer such that
2
b
≤
n
2^b \le n
2
b
≤
n
. Prove that
a
≤
b
+
3
a \le b + 3
a
≤
b
+
3
.
number theory
inequalities
algebra