A161003 - OEIS

%I #23 Mar 29 2017 10:31:11

%S 2,2,4,3,2,4,2,3,8,6,4,3,2,8,5,2,9,4,6,16,3,2,5,12,2,3,8,6,4,9,2,16,7,

%T 10,3,4,18,5,8,3,2,12,2,9,32,5,6,4,3,10,24,2,15,4,7,6,16,27,2,12,5,2,

%U 3,8,18,7,4,3,2,5,32,14,9,20,6,8,15,2,36,10,3,16,6,5,4,9,2,7,24,11,2,3,4

%N A list of the composite numbers divided by their largest prime factors.

%C a(A120389(n)) = A000040(n). - _Gionata Neri_, May 07 2015

%C For n >= 2, a(x) = n where x = A066246(n*A006530(n)). - _Robert Israel_, May 07 2015

%H Robert Israel, <a href="/A161003/b161003.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A002808(n)/A052369(n). - _Robert Israel_, May 07 2015

%e n=1 4/2; n=2 6/3; n=3 8/2.

%p with(numtheory): a := proc (n) if isprime(n) = false then n/factorset(n)[nops(factorset(n))] else end if end proc: seq(a(n), n = 2 .. 130); # _Emeric Deutsch_, Jun 27 2009

%t With[{cmps=Select[Range[200],CompositeQ]},#/FactorInteger[#][[-1,1]]&/@ cmps] (* _Harvey P. Dale_, Mar 29 2017 *)

%Y Cf. A000040, A002808, A006530, A052369, A066246, A120389, A161004, A160180.

%K nonn

%O 1,1

%A Trevor Cassiliano (casstjc(AT)gmail.com), Jun 01 2009

%E Extended by _Emeric Deutsch_, Jun 27 2009