A028261 Numbers whose total number of prime factors (counting multiplicity) is squarefree.

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74

Offset: 1

Author

Daniel Asimov (dan(AT)research.att.com)

Keywords

• nonn

Comments

The complement is 1, 16, 24, 36, 40, 54, 56, 60, 81, 84, 88, 90, 100.. and contains all entries of A014613, all of A046310, all of A046312 etc. - R. J. Mathar, Dec 15 2015

Crossrefs

Cf. A001222, A005117.

Programs

PARI

isok(n) = issquarefree(bigomega(n)); \\ Michel Marcus, Aug 31 2013