A084679 Composite numbers with coprime numbers of prime factors with and without repetition.

12, 18, 20, 28, 44, 45, 48, 50, 52, 60, 63, 68, 72, 75, 76, 80, 84, 90, 92, 98, 99, 108, 112, 116, 117, 120, 124, 126, 132, 140, 147, 148, 150, 153, 156, 162, 164, 168, 171, 172, 175, 176, 180, 188, 192, 198, 200, 204, 207, 208, 212, 220, 228, 234, 236, 242

Offset

1,1

Comments

A001221(a(n))>1 and GreatestCommonDivisor(A001221(a(n)), A001222(a(n)))=1;

a(n)=A070011(n) for n<228, but A070011(228)=840=7*5*3*2^3 with omega=4 and bigOmega=6, as GCD(4,6)=2>1 840 is not a term.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Prog

(PARI) is(n)=my(f=factor(n)[, 2]); #f>1 && gcd(vecsum(f), #f)==1 \\ Charles R Greathouse IV, Oct 19 2015

Crossrefs

Different from A070011.

Sequence in context: A351201 A359892 A070011 * A072588 A267117 A187039

Adjacent sequences: A084676 A084677 A084678 * A084680 A084681 A084682

Keyword

nonn

Author

Reinhard Zumkeller, Jun 28 2003

Status

approved