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A162902
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An increasing sequence of alternatingly squarefree and not squarefree numbers.
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0
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1, 4, 5, 8, 10, 12, 13, 16, 17, 18, 19, 20, 21, 24, 26, 27, 29, 32, 33, 36, 37, 40, 41, 44, 46, 48, 51, 52, 53, 54, 55, 56, 57, 60, 61, 63, 65, 68, 69, 72, 73, 75, 77, 80, 82, 84, 85, 88, 89, 90, 91, 92, 93, 96, 97, 98, 101, 104, 105, 108, 109, 112, 113, 116, 118, 120, 122
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Composed of elements of A005117 at odd indices and of A013929 at even indices
such that first differences of the combined sequence remain positive and minimal.
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MATHEMATICA
| f[n_]:=Module[{a=m=0}, Do[If[FactorInteger[n][[m, 2]]>1, a=1], {m, Length[FactorInteger[n]]}]; a]; q=0; lst={}; Do[If[f[n]==q, If[q==1, q=0, q=1]; AppendTo[lst, n]], {n, 6!}]; lst
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CROSSREFS
| Cf. A005117
Sequence in context: A064394 A092022 A190200 * A026491 A174396 A033157
Adjacent sequences: A162899 A162900 A162901 * A162903 A162904 A162905
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KEYWORD
| nonn
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AUTHOR
| Vladimir Orlovsky (4vladimir(AT)gmail.com), Jul 16 2009
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EXTENSIONS
| Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 21 2009
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