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A219547
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Numbers k such that 2 times the least prime factor of 2^k + 1 is not the least m > 1 that divides sigma_k(m).
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1
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8, 16, 32, 40, 48, 56, 64, 80, 88, 96, 104, 112, 128, 136, 152, 160, 176, 184, 192, 200, 208, 224, 232, 240, 248, 256, 272, 280, 296, 304, 320, 328, 336, 344, 352, 368, 376, 384, 392, 400, 416, 424, 440, 448, 464, 472, 480, 488, 496
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OFFSET
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1,1
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COMMENTS
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The corresponding least prime factors of 2^k + 1 are A219548.
See A007691 for references, links, and additional comments.
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LINKS
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FORMULA
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EXAMPLE
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A066135(n) = 6,10,6,34,6,10,6 = 2*A002586(n) for n = 1,2,3,4,5,6,7, and A066135(8) = 84 < 2*257 = 2*A002586(8), so a(1) = 8.
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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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