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A125242
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Numbers k such that binomial(5k, k) - 1 is prime.
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5
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5, 71, 111, 187, 239, 247, 473, 628, 847, 1478, 2687, 3530, 5175, 9113, 10968, 15039, 28929, 35649, 43481, 44455
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Do[f=Binomial[5n, n]-1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]
Select[Range[45000], PrimeQ[Binomial[5#, #]-1]&] (* Harvey P. Dale, Jan 02 2022 *)
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CROSSREFS
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KEYWORD
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hard,more,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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