A283069 - OEIS

%I #24 Oct 19 2024 15:57:32

%S 1,2,1,3,4,5,6,1,3,7,8,9,10,11,5,12,1,13,14,15,7,16,17,18,19,20,9,21,

%T 22,23,24,11,25,26,27,28,29,13,30,1,31,5,32,33,15,34,35,36,37,38,17,

%U 39,40,41,42,1,19,43,7,44,45,46,47,21,48,49,50,51,23,52,53

%N A283050(n) divided by the square of its least prime factor.

%C Sequence contains all positive integers. Every positive integer except 1 can be term of this sequence only finitely many times (i.e., 8 is a term only for a(11) = 8). - _Altug Alkan_, Feb 28 2017

%H Robert Israel, <a href="/A283069/b283069.txt">Table of n, a(n) for n = 1..10000</a>

%H Ana Rechtman, <a href="http://images-archive.math.cnrs.fr/Fevrier-2017-4e-defi.html">Février 2017, 4e défi</a>, Images des Mathématiques, CNRS, 2017.

%F a(n) = A283050(n) / A020639(A283050(n))^2. - _Altug Alkan_, Feb 28 2017

%p Res:= NULL:

%p for n from 2 to 1000 do

%p   p:= min(numtheory:-factorset(n));

%p   if n mod p^2 = 0 then Res:= Res, n/p^2; fi

%p od:

%p Res; # _Robert Israel_, Feb 28 2017

%t DeleteCases[Table[n/FactorInteger[n][[1, 1]]^2, {n, 2, 300}], k_ /; ! IntegerQ@ k] (* _Michael De Vlieger_, Feb 28 2017 *)

%o (PARI) lista(nn) = {for(n=2, nn, if (!(n % (p=factor(n)[1,1]^2)), print1(n/p, ", ")););}

%Y Cf. A126773, A283050.

%K nonn,look

%O 1,2

%A _Michel Marcus_, Feb 28 2017