

A162902


An increasing sequence of alternatingly squarefree and not squarefree 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: A141220 A092022 A190200 * A026491 A255491 A214026
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



