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Search: id:A054903
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| A054903 |
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Composite numbers n such that sigma(n)+6 = sigma(n+6), where sigma=A000203. |
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+0
5
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| 104, 147, 596, 1415, 4850, 5337, 370047, 1630622, 35020303, 120221396, 3954451796
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Complement of A023201 with respect to A015914.
Intersection of A015914 and A018252.
Below 1000000 there are only 7 such composite numbers, compared with more than 16000 primes.
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REFERENCES
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J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 104, p. 37, Ellipses, Paris 2008.
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EXAMPLE
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n=104,Sigma[104]+6=210+6=216=Sigma[104+6]=Sigma[110]
a(4) = 1415 = 5*283, 1415+6 = 1421 = 7*7*29:
sigma(1415) = 1+5+283+1415 = 1704,
sigma(1421) = 1+7+29+49+203+1421 = 1710 = sigma(1415)+6.
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CROSSREFS
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Cf. A015913-A015917, A023200-A023203, A046133, A001359, A054799.
Sequence in context: A095641 A055036 A052476 this_sequence A074228 A044336 A044717
Adjacent sequences: A054900 A054901 A054902 this_sequence A054904 A054905 A054906
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KEYWORD
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nonn,more
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), May 23 2000
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EXTENSIONS
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More terms from Jud McCranie (j.mccranie(AT)comcast.net), May 25 2000
New definition from Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 27 2009
Edited by N. J. A. Sloane (njas(AT)research.att.com), Jan 31 2009 at the suggestion of R. J. Mathar.
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