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A111457
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Number of semiprime < n-th prime.
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0
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0, 0, 1, 2, 4, 4, 6, 6, 8, 10, 10, 13, 15, 15, 16, 18, 21, 21, 23, 24, 24, 26, 27, 30, 34, 34, 34, 35, 35, 36, 42, 43, 45, 45, 50, 50, 51, 54, 55, 56, 58, 58, 61, 61, 62, 62, 68, 75, 76, 76, 76, 78, 78, 80, 82, 84, 86, 86, 87, 88, 88, 91, 98, 99, 99, 100, 106, 108, 111, 111
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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MATHEMATICA
| s = Select[Range@1000, Plus @@ Last /@ FactorInteger@ # == 2 &]; Table[ Length@Select[s, # < Prime@n &], {n, 70}] (* Robert G. Wilson v *)
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CROSSREFS
| Sequence in context: A014684 A113638 A187323 * A161765 A164798 A087554
Adjacent sequences: A111454 A111455 A111456 * A111458 A111459 A111460
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KEYWORD
| nonn
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AUTHOR
| Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Nov 15 2005
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(at)rgwv.com) and Stefan Steinerberger (hansibal(AT)hotmail.com), Nov 18 2005
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