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A309347
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Numbers that are the sum of two refactorable numbers whose difference is refactorable.
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1
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3, 10, 17, 27, 36, 48, 54, 60, 84, 88, 96, 104, 108, 112, 120, 128, 132, 136, 144, 152, 156, 168, 176, 180, 184, 192, 200, 204, 208, 216, 224, 228, 232, 240, 248, 252, 256, 264, 272, 276, 280, 288, 296, 300, 304, 312, 324, 328, 336, 344, 348, 352, 360, 368
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..54.
Eric Weisstein's World of Mathematics, Refactorable Number
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MATHEMATICA
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Flatten[Table[If[Sum[ (1 - Ceiling[(n - 2 i)/DivisorSigma[0, n - 2 i]] + Floor[(n - 2 i)/DivisorSigma[0, n - 2 i]]) (1 - Ceiling[i/DivisorSigma[0, i]] + Floor[i/DivisorSigma[0, i]]) (1 - Ceiling[(n - i)/DivisorSigma[0, n - i]] + Floor[(n - i)/DivisorSigma[0, n - i]]), {i, Floor[(n - 1)/2]}] > 0, n, {}], {n, 400}]]
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CROSSREFS
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Cf. A033950.
Sequence in context: A219726 A017017 A297665 * A273235 A309351 A003615
Adjacent sequences: A309344 A309345 A309346 * A309348 A309349 A309350
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KEYWORD
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nonn
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AUTHOR
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Wesley Ivan Hurt, Jul 24 2019
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STATUS
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approved
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