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A353300
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Numbers k such that A004394(k)-1 is prime.
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3
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3, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 19, 20, 24, 25, 26, 30, 32, 41, 47, 48, 49, 51, 57, 59, 76, 82, 83, 92, 104, 105, 117, 119, 131, 134, 137, 139, 143, 154, 166, 170, 172, 180, 209, 214, 215, 216, 217, 227, 231, 234, 247, 265, 269, 271, 284, 317, 327, 348
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OFFSET
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1,1
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COMMENTS
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First differs from A306588 at n=15.
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LINKS
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EXAMPLE
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3 is a term since A004394(3)-1 = 4-1 = 3 is prime.
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MATHEMATICA
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s = {}; abm = 0; k = 0; Do[ab = DivisorSigma[-1, n]; If[ab > abm, abm = ab; k++; If[PrimeQ[n - 1], AppendTo[s, k]]], {n, 1, 10^6}]; s
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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