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A071311
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Squarefree numbers k with largest prime factor = floor(sqrt(k)).
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1
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30, 182, 195, 399, 870, 1023, 1406, 1443, 1722, 2915, 3782, 4623, 5402, 7055, 8099, 10302, 10815, 11990, 12099, 12882, 12995, 16383, 17423, 18906, 19599, 24806, 24963, 26895, 30102, 32942, 33123, 37442, 37635, 39999, 44943, 52670, 52899, 54755, 63503, 66306, 66563
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OFFSET
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1,1
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COMMENTS
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If k = p(1)*p(2)*...p(r) is in the sequence, where p(r) is the largest prime factor, then p(1)*p(2)*...*p(r-1) - p(r) = 1 or 2.
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LINKS
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EXAMPLE
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1023 = 3*11*31 and sqrt(1023) = 31.98437... hence 1023 is in the sequence.
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MATHEMATICA
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Select[Range[2, 50000], SquareFreeQ[#] && FactorInteger[#][[-1, 1]] == Floor[Sqrt[#]] &] (* Amiram Eldar, Apr 23 2022 *)
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PROG
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(PARI) for(n=2, 100000, if(issquarefree(n)*component(component(factor(n), 1), omega(n))==floor(sqrt(n)), print1(n, ", ")))
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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