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A100598
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Numbers k such that (prime(k)-1)! + prime(k)^8 is prime.
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2
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OFFSET
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1,2
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COMMENTS
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k = {1, 2, 4, 5, 8, 10} yields primes p(k) = {2, 3, 7, 11, 19, 29}. 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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EXAMPLE
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a(1) = 1 because (prime(1)-1)! + prime(1)^8 = (2-1)! + 2^8 = 257 is the smallest prime of that form.
a(5) = 8 because (prime(8)-1)! + prime(8)^8 = (19-1)! + 19^8 = 304888344611713861001750412961 is the 5th smallest prime of that form.
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MATHEMATICA
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PROG
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(PARI) is(k) = ispseudoprime((prime(k)-1)! + prime(k)^8); \\ Jinyuan Wang, Apr 10 2020
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CROSSREFS
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KEYWORD
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nonn,hard,more,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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