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A003624
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Duffinian numbers: n composite and relatively prime to sigma (n).
(Formerly M3324)
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2
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4, 8, 9, 16, 21, 25, 27, 32, 35, 36, 39, 49, 50, 55, 57, 63, 64, 65, 75, 77, 81, 85, 93, 98, 100, 111, 115, 119, 121, 125, 128, 129, 133, 143, 144, 155, 161, 169, 171, 175, 183, 185, 187, 189, 201, 203, 205, 209, 215, 217, 219, 221, 225, 235, 237, 242, 243, 245, 247
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| T. Koshy, Elementary number theory with applications, Academic Press, 2002, p. 141, exerc. 6,7,8 and 9.
L. Richard Duffy, "The Duffinian Numbers", J. Rec. Math., 12 (1979), 112-115.
J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 64.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000
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CROSSREFS
| Cf. A014567
Sequence in context: A134344 A119315 A010390 * A100657 A140104 A127398
Adjacent sequences: A003621 A003622 A003623 * A003625 A003626 A003627
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein
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