A162966 - OEIS

A162966

Union of 1 and nonsquarefree numbers (A013929).

1, 4, 8, 9, 12, 16, 18, 20, 24, 25, 27, 28, 32, 36, 40, 44, 45, 48, 49, 50, 52, 54, 56, 60, 63, 64, 68, 72, 75, 76, 80, 81, 84, 88, 90, 92, 96, 98, 99, 100, 104, 108, 112, 116, 117, 120, 121, 124, 125, 126, 128, 132, 135, 136, 140, 144, 147, 148, 150, 152, 153, 156, 160

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Or, the natural numbers that are not products of distinct primes. Also, number of prime divisors of n < number of nonprime divisors of n. - Juri-Stepan Gerasimov, Nov 10 2009

LINKS

Table of n, a(n) for n=1..63.

MATHEMATICA

t = {1}; Do[If[Max[Transpose[FactorInteger[n]][[2]]] > 1, AppendTo[t, n]], {n, 2, 160}]; t (* Jayanta Basu, Apr 30 2013 *)

PROG

(PARI) is(n)=!issquarefree(n)||n==1 \\ Charles R Greathouse IV, Apr 04 2014

CROSSREFS

Cf. A013929.

Sequence in context: A289553 A345212 A013929 * A375142 A350137 A359470

Adjacent sequences: A162963 A162964 A162965 * A162967 A162968 A162969

KEYWORD

nonn,less

AUTHOR

Jaroslav Krizek, Jul 19 2009

STATUS

approved