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A180422
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Largest prime immediately preceding a Fibonacci number.
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4
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2, 3, 7, 11, 19, 31, 53, 83, 139, 229, 373, 607, 983, 1583, 2579, 4177, 6763, 10939, 17707, 28649, 46351, 75017, 121379, 196387, 317797, 514219, 832003, 1346249, 2178283, 3524569, 5702867, 9227443, 14930341, 24157811, 39088157, 63245971
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OFFSET
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4,1
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COMMENTS
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Limit ratio of two consecutive elements of this sequence is phi=1.61803... the golden ratio.
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LINKS
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EXAMPLE
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a(7)=53 that is the prime number preceding 55=fib(10).
fib(1)=1, fib(2)=1 and fib(3)=2 are not accounted.
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MATHEMATICA
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NextPrime[#, -1]&/@Fibonacci[Range[4, 40]] (* Harvey P. Dale, Oct 31 2013 *)
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PROG
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(PARI) a(n)=precprime(fibonacci(n)-1)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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