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A245801
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Positive n such that Lucas(3*n) - Fibonacci(n) is a prime.
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1
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1, 2, 28, 58, 98, 118, 212, 238, 350, 478, 883, 2660, 3971, 21491
(list;
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history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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n=0 would give the prime 2 but positive n is required. Some terms correspond to probable primes. a(15) > 40000. - Jens Kruse Andersen, Aug 04 2014
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LINKS
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MAPLE
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with(combinat): A245801:=n->`if`(isprime(fibonacci(3*n+1)+fibonacci(3*n-1)-fibonacci(n)), n, NULL): seq(A245801(n), n=1..1000); # Wesley Ivan Hurt, Aug 04 2014
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MATHEMATICA
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Select[Range[3000], PrimeQ[LucasL[3 #] - Fibonacci[#]] &]
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PROG
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(Magma) [n: n in [1..800] | IsPrime(Lucas(3*n) - Fibonacci(n))];
(Python)
import sympy
{print(n, end=', ') for n in range(10**3) if sympy.isprime(sympy.lucas(3*n)-sympy.fibonacci(n))} # Derek Orr, Aug 03 2014
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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