A289553 Numbers that are not the product of two distinct noncomposite numbers (A008578).

1, 4, 8, 9, 12, 16, 18, 20, 24, 25, 27, 28, 30, 32, 36, 40, 42, 44, 45, 48, 49, 50, 52, 54, 56, 60, 63, 64, 66, 68, 70, 72, 75, 76, 78, 80, 81, 84, 88, 90, 92, 96, 98, 99, 100, 102, 104, 105, 108, 110, 112, 114, 116, 117, 120, 121, 124, 125, 126, 128, 130, 132

Offset: 1

Author

Jaroslav Krizek, Jul 07 2017

Keywords

• nonn

Comments

Numbers k such that tau(k) = A000005(k) is not equal to 2*omega(k) = 2*A001221(k).

Examples

			Number 6 is not in the sequence because 6 = 2 * 3.
		

Crossrefs

Complement of A167171.

Cf. A246716 (with two distinct primes), A008578 (with two distinct nonprimes), A289555 (with two distinct composites).

Programs

Magma

[n: n in [1..1000] | NumberOfDivisors(n) ne 2*#PrimeDivisors(n)];