A052369 Largest prime factor of n, where n runs through composite numbers.

2, 3, 2, 3, 5, 3, 7, 5, 2, 3, 5, 7, 11, 3, 5, 13, 3, 7, 5, 2, 11, 17, 7, 3, 19, 13, 5, 7, 11, 5, 23, 3, 7, 5, 17, 13, 3, 11, 7, 19, 29, 5, 31, 7, 2, 13, 11, 17, 23, 7, 3, 37, 5, 19, 11, 13, 5, 3, 41, 7, 17, 43, 29, 11, 5, 13, 23, 31, 47, 19, 3, 7, 11, 5, 17, 13, 7, 53, 3, 11, 37, 7, 19, 23

Offset

1,1

Links

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

Formula

a(n) = A006530(A002808(n)). [Reinhard Zumkeller, Aug 25 2008]

Example

First composite is 4, largest prime factor is 2, so a(1)=2.

Maple

map(t -> max(numtheory:-factorset(t)), remove(isprime, [$2..10^3])); # Robert Israel, Aug 10 2014

Mathematica

FactorInteger[#][[-1, 1]]&/@Select[Range[150], CompositeQ] (* Harvey P. Dale, Jan 24 2016 *)

Prog

(Magma) [ D[ #D]: n in [2..115] | not IsPrime(n) where D is PrimeDivisors(n) ]; // [Klaus Brockhaus, Jun 23 2009]
(PARI) forcomposite(n=1, 1e2, p=factor(n)[omega(n), 1]; print1(p, ", ")) \\ Felix Fröhlich, Aug 08 2014

Crossrefs

Cf. A002808, A006530, A056608. [From Reinhard Zumkeller, Aug 25 2008]

Sequence in context: A046147 A251865 A306196 * A110976 A318271 A236483

Adjacent sequences: A052366 A052367 A052368 * A052370 A052371 A052372

Keyword

nonn,easy

Author

Michael Contente (mec1000(AT)aol.com), Mar 08 2000

Extensions

More terms from James A. Sellers, Mar 09 2000

Status

approved