A161003 A list of the composite numbers divided by their largest prime factors.

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, 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, 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

Offset: 1

Author

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

Keywords

• nonn

Comments

a(A120389(n)) = A000040(n). - Gionata Neri, May 07 2015

For n >= 2, a(x) = n where x = A066246(n*A006530(n)). - Robert Israel, May 07 2015

Examples

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

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

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

Programs

Maple

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

Mathematica

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

Formula

a(n) = A002808(n)/A052369(n). - Robert Israel, May 07 2015

Extensions

Extended by Emeric Deutsch, Jun 27 2009