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A082997
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a(n) = card{ x <= n : omega(x) = 2 }.
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0
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0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 4, 5, 5, 5, 6, 6, 7, 8, 9, 9, 10, 10, 11, 11, 12, 12, 12, 12, 12, 13, 14, 15, 16, 16, 17, 18, 19, 19, 19, 19, 20, 21, 22, 22, 23, 23, 24, 25, 26, 26, 27, 28, 29, 30, 31, 31, 31, 31, 32, 33, 33, 34, 34, 34, 35, 36, 36, 36, 37, 37, 38, 39, 40, 41
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,10
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REFERENCES
| G. Tenenbaum, Introduction a la theorie analytique et probabiliste des nombres, p. 203, Publications de l'Institut Cartan,1990.
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FORMULA
| a(n) ~ (n/log(n))*log(log(n))
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PROG
| (PARI) a(n)=sum(i=1, n, if(omega(i)-2, 0, 1))
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CROSSREFS
| Cf. A025528, A072000.
Sequence in context: A076918 A162620 A194249 * A085970 A066683 A055038
Adjacent sequences: A082994 A082995 A082996 * A082998 A082999 A083000
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), May 30 2003
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