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Search: id:A000977
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| A000977 |
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Numbers that are divisible by at least three different primes. |
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+0
7
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| 30, 42, 60, 66, 70, 78, 84, 90, 102, 105, 110, 114, 120, 126, 130, 132, 138, 140, 150, 154, 156, 165, 168, 170, 174, 180, 182, 186, 190, 195, 198, 204, 210, 220, 222, 228, 230, 231, 234, 238, 240, 246, 252, 255, 258, 260, 264, 266, 270, 273
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n+1)-a(n) seems bounded and sequence appears to give n such that the number of integers of the form nk/(n+k) k>=1 is not equal to sum{ d | n, omega(d) } (i.e. n such that A062799(n) is not equal to A063647(n) ) - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 27 2002
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 844.
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LINKS
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
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MATHEMATICA
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DeleteCases[Table[If[Count[PrimeQ[Divisors[i]], True] >= 3, i, 0], {i, 1, 274}], 0]
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CROSSREFS
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Cf. A033992, A007774, A000961, A033993, A051270.
Sequence in context: A090790 A090800 A114816 this_sequence A033992 A091454 A136152
Adjacent sequences: A000974 A000975 A000976 this_sequence A000978 A000979 A000980
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Vit Planocka (planocka(AT)mistral.cz), Sep 17 2002
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