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A180422 Largest prime immediately preceding a Fibonacci number. 4


%S 2,3,7,11,19,31,53,83,139,229,373,607,983,1583,2579,4177,6763,10939,

%T 17707,28649,46351,75017,121379,196387,317797,514219,832003,1346249,

%U 2178283,3524569,5702867,9227443,14930341,24157811,39088157,63245971

%N Largest prime immediately preceding a Fibonacci number.

%C Limit ratio of two consecutive elements of this sequence is phi=1.61803... the golden ratio.

%H Harvey P. Dale, <a href="/A180422/b180422.txt">Table of n, a(n) for n = 4..1000</a>

%e a(7)=53 that is the prime number preceding 55=fib(10).

%e fib(1)=1, fib(2)=1 and fib(3)=2 are not accounted.

%t NextPrime[#,-1]&/@Fibonacci[Range[4,40]] (* _Harvey P. Dale_, Oct 31 2013 *)

%o (PARI) a(n)=precprime(fibonacci(n)-1)

%Y Cf. A138184, A000045

%K nonn

%O 4,1

%A _Carmine Suriano_, Sep 03 2010

%E Program and cross-ref from _Charles R Greathouse IV_, Sep 08 2010

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Last modified April 18 16:51 EDT 2021. Contains 343089 sequences. (Running on oeis4.)