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A100602
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Numbers k such that (prime(k)-1)! + prime(k)^5 is prime.
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1
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OFFSET
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1,1
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COMMENTS
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k = {6, 8, 11, 17} yields primes p(k) = {13, 19, 31, 59}. There are no more such k up to k=100. Computed in collaboration with Ray Chandler.
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LINKS
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FORMULA
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Numbers k such that (prime(k)-1)! + prime(k)^5 is prime, where prime(k) is the k-th prime.
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EXAMPLE
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a(1) = 6 because (prime(6)-1)! + prime(6)^5 = (13-1)! + 13^5 = 479372893 is the first prime of this form.
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MATHEMATICA
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PROG
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(PARI) is(k) = ispseudoprime((prime(k)-1)! + prime(k)^5); \\ Jinyuan Wang, Apr 10 2020
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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