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Search: id:A125527
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| A125527 |
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Number of semiprimes <= 2^n. |
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+0
4
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| 0, 1, 2, 6, 10, 22, 42, 82, 157, 304, 589, 1124, 2186, 4192, 8110, 15658, 30253, 58546, 113307, 219759, 426180, 827702, 1608668, 3129211, 6091437, 11868599, 23140878, 45150717, 88157689, 172235073, 336717854, 658662065, 1289149627, 2524532330
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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Robert G. Wilson v, Table of n, a(n) for n = 1..49 [File corrected Mar 12 2007]
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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MATHEMATICA
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SemiPrimePi[n_] := Sum[ PrimePi[ n/Prime@i] - i + 1, {i, PrimePi@ Sqrt@n}]; Table[ SemiPrimePi[2^n], {n, 47}]
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CROSSREFS
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Cf. A126279, A066265, A007053, A127396.
Sequence in context: A001172 A167512 A055895 this_sequence A049750 A134016 A072297
Adjacent sequences: A125524 A125525 A125526 this_sequence A125528 A125529 A125530
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 29 2006
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