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A221018 Number n such that Fibonacci(n) is divisible by n, n + 1 and n - 1.

%I A221018 #21 Mar 26 2021 09:25:08
%S A221018 108,2688,3528,4968,6480,15288,18048,20808,21000,25308,35448,47520,
%T A221018 62928,68208,81648,82008,97608,103968,108288,116928,137088,139968,
%U A221018 151848,162288,196560,197568,200928,235008,238728,253368,278208,363888,379008,400248,444528,449568,457608
%N A221018 Number n such that Fibonacci(n) is divisible by n, n + 1 and n - 1.
%C A221018 Numbers n such that Fibonacci(n) mod n = Fibonacci(n) mod (n-1) = Fibonacci(n) mod (n+1) = 0.
%C A221018 Subsequence of A023172.
%H A221018 Chai Wah Wu, <a href="/A221018/b221018.txt">Table of n, a(n) for n = 1..200</a>
%o A221018 (Python)
%o A221018 prpr, prev = 0, 1
%o A221018 for n in range(2, 100000):
%o A221018     prpr, prev = prev, prpr+prev
%o A221018     if n%2: continue
%o A221018     if (prev % n, prev % (n-1), prev % (n+1)) == (0, 0, 0):
%o A221018         print(n, end=", ")
%Y A221018 Cf. A000045, A023172, A225219.
%K A221018 nonn
%O A221018 1,1
%A A221018 _Alex Ratushnyak_, May 03 2013