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Numbers m such that m divides Fibonacci(m+1).
7

%I #26 Aug 29 2021 11:59:10

%S 1,2,3,7,13,17,23,37,43,47,53,67,73,83,97,103,107,113,127,137,157,163,

%T 167,173,193,197,223,227,233,257,263,277,283,293,307,313,317,323,337,

%U 347,353,367,373,377,383,397,433,443,457,463,467,487,503,523,547,557

%N Numbers m such that m divides Fibonacci(m+1).

%C Equals A003631 union A069107.

%C Let u(1)=u(2)=1 and (m+2)*u(m+2) = (m+1)*u(m+1) + m*u(m); then sequence gives values of k such that u(k) is an integer.

%H Reinhard Zumkeller, <a href="/A069104/b069104.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[6! ],IntegerQ[Fibonacci[ #+1]/# ]&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2009 *)

%o (Haskell)

%o import Data.List (elemIndices)

%o a069104 n = a069104_list !! (n-1)

%o a069104_list =

%o map (+ 1) $ elemIndices 0 $ zipWith mod (drop 2 a000045_list) [1..]

%o -- _Reinhard Zumkeller_, Oct 13 2011

%o (PARI) is(n)=((Mod([1,1;1,0],n))^n)[1,1]==0 \\ _Charles R Greathouse IV_, Feb 03 2014

%Y Cf. A000045, A023172, A123976, A159051.

%K easy,nonn

%O 1,2

%A _Benoit Cloitre_, Apr 06 2002

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Last modified September 23 18:10 EDT 2024. Contains 376182 sequences. (Running on oeis4.)