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A115170
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Non-cubefree numbers n such that 2n+1 is also non-cubefree (A046099).
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2
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40, 256, 312, 472, 688, 904, 1120, 1200, 1312, 1336, 1552, 1768, 1984, 2187, 2200, 2312, 2416, 2456, 2632, 2848, 2875, 3064, 3280, 3312, 3429, 3496, 3712, 3928, 3944, 4144, 4312, 4360, 4576, 4792, 5008, 5224, 5312, 5440, 5562, 5656, 5872, 6088, 6250, 6304, 6312, 6345, 6520, 6655, 6688, 6736, 6952
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OFFSET
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1,1
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COMMENTS
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The probability that a random integer is cubefree is 1/zeta(3) (see A088453).
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LINKS
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R. J. Mathar, Table of n, a(n) for n = 1..700
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EXAMPLE
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312 is there because 2^3 divides 312 and 5^3 divides 312*2+1.
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CROSSREFS
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Cf. A005384 (n and 2n+1 prime), A046099, A088453, A111153 (n and 2n+1 semiprime), A117204 (n and 2n+1 squarefree), A115228.
Sequence in context: A229632 A223426 A290127 * A247406 A229588 A334121
Adjacent sequences: A115167 A115168 A115169 * A115171 A115172 A115173
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post, Mar 03 2006
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EXTENSIONS
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Edited by Don Reble, Mar 05 2006
2875 inserted by R. J. Mathar, Dec 08 2015
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STATUS
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approved
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