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A056912
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Odd squarefree numbers for which the number of prime divisors is odd.
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6
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3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 105, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 165, 167, 173, 179, 181, 191, 193, 195, 197, 199, 211, 223, 227, 229, 231, 233, 239, 241, 251, 255
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Liouville function lambda(n) (A008836) is negative.
m is a term iff mu(m)^m < 0 (A080323(a(n))<0), where mu is the Moebius function (A008683). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 14 2003
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REFERENCES
| H. Gupta, A formula for L(n), J. Indian Math. Soc., 7 (1943), 68-71.
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EXAMPLE
| a(27) = 3*5*7 = 105 is the least nonprime.
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CROSSREFS
| Cf. A056911, A056913, A008836, A026424, A028260.
Sequence in context: A067019 A132106 A093893 * A075763 A074918 A175524
Adjacent sequences: A056909 A056910 A056911 * A056913 A056914 A056915
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KEYWORD
| easy,nonn
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AUTHOR
| James A. Sellers (sellersj(AT)math.psu.edu), Jul 07 2000
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