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A162902 An increasing sequence of alternatingly squarefree and nonsquarefree numbers. 0
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; text; internal format)
OFFSET

1,2

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.

LINKS

Table of n, a(n) for n=1..67.

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

CROSSREFS

Cf. A005117.

Sequence in context: A340762 A092022 A190200 * A026491 A255491 A292658

Adjacent sequences:  A162899 A162900 A162901 * A162903 A162904 A162905

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jul 16 2009

EXTENSIONS

Edited by R. J. Mathar, Jul 21 2009

STATUS

approved

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Last modified June 12 14:20 EDT 2021. Contains 344956 sequences. (Running on oeis4.)