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A146166
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Odd squarefree semiprimes.
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12
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15, 21, 33, 35, 39, 51, 55, 57, 65, 69, 77, 85, 87, 91, 93, 95, 111, 115, 119, 123, 129, 133, 141, 143, 145, 155, 159, 161, 177, 183, 185, 187, 201, 203, 205, 209, 213, 215, 217, 219, 221, 235, 237, 247, 249, 253, 259, 265, 267, 287, 291
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Subsequence of A056913. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 29 2008]
These numbers n have the property that n is a Fermat pseudoprime for at least two bases 1 < b < n - 1. That is, b^(n - 1) = 1 (mod n). See sequence A175101 for a count of the number of bases.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000
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MATHEMATICA
| max = 300; A146166 = Sort@Flatten@Table[Prime[m] Prime[n], {n, 3, Ceiling[PrimePi[max/3]]}, {m, 2, n - 1}]; Select[A146166, # < max &] (* From Alonso del Arte based on Robert G. Wilson v's program for A006881, Oct 24 2011 *)
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CROSSREFS
| Cf. A001358 (semiprimes), A046388 (odd numbers with exactly 2 distinct prime factors).
Sequence in context: A046388 A098905 A024556 * A056913 A002557 A128907
Adjacent sequences: A146163 A146164 A146165 * A146167 A146168 A146169
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KEYWORD
| nonn
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AUTHOR
| W. Bomfim (webonfim(AT)bol.com.br), Oct 27 2008
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