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A073846
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a(1) = 1 and then every even term is prime and every odd term is composite.
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6
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1, 2, 4, 3, 6, 5, 8, 7, 9, 11, 10, 13, 12, 17, 14, 19, 15, 23, 16, 29, 18, 31, 20, 37, 21, 41, 22, 43, 24, 47, 25, 53, 26, 59, 27, 61, 28, 67, 30, 71, 32, 73, 33, 79, 34, 83, 35, 89, 36, 97, 38, 101, 39, 103, 40, 107, 42, 109, 44, 113, 45, 127, 46, 131, 48, 137, 49, 139, 50
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Equals A067747 shifted by one position. a(n) = A067747(n-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 01 2007
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MATHEMATICA
| Composite[n_Integer] := FixedPoint[n + PrimePi[ # ] + 1 &, n]; Join[{1}, Flatten[ Transpose[{Table[Prime[n], {n, 1, 35}], Table[Composite[n], {n, 1, 35}]}]]]
f[upto_]:=Module[{prs=Prime[Range[PrimePi[upto]]], comps}, comps= Complement[ Range[upto], prs]; Riffle[Take[comps, Length[prs]], prs]]; f[150] (* From Harvey P. Dale, Dec 03 2011 *)
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CROSSREFS
| Sequence in context: A086305 A073898 A067747 * A110458 A114112 A113981
Adjacent sequences: A073843 A073844 A073845 * A073847 A073848 A073849
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KEYWORD
| easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 14 2002
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com) and Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 16 2002
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