A189716 - OEIS

%I #14 Mar 08 2021 02:48:55

%S 2,3,5,8,11,12,14,17,18,20,21,23,26,27,29,30,32,35,38,39,41,44,45,47,

%T 48,50,53,56,57,59,62,65,66,68,71,72,74,75,77,80,83,84,86,89,92,93,95,

%U 98,99,101,102,104,107,108,110,111,113,116,119,120,122,125,126,128,129,131,134,137,138,140,143,146,147,149,152,153,155,156,158

%N Numbers k such that A156595(k-1) = 1; complement of A189715.

%C See A156595.

%C Numbers whose squarefree part is congruent modulo 9 to 2, 3, 5 or 8. - _Peter Munn_, May 17 2020

%C The asymptotic density of this sequence is 1/2. - _Amiram Eldar_, Mar 08 2021

%H Amiram Eldar, <a href="/A189716/b189716.txt">Table of n, a(n) for n = 1..10000</a>

%t (See A189715.)

%t f[p_, e_] := (p^Mod[e, 2]); sqfpart[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[160], MemberQ[{2, 3, 5, 8}, Mod[sqfpart[#], 9]] &] (* _Amiram Eldar_, Mar 08 2021 *)

%Y Cf. A007913, A156595, A189715, A189717.

%Y Union of A055041 and A055048.

%K nonn

%O 1,1

%A _Clark Kimberling_, Apr 26 2011

%E Name enhanced by _Peter Munn_, May 17 2020