A171995 Twin natural nonprimes with nonprime number of prime factors.

1, 625, 1715, 1925, 2125, 2875, 2975, 3575, 3773, 4165, 4225, 4235, 4625, 5125, 5375, 5425, 5635, 5831, 5875, 5915, 6517, 6625, 7007, 7225, 7315, 7375, 7595, 7625, 7735, 7889, 7975, 8075, 8225, 8281, 8855, 8875, 9025, 9425, 9775, 9875, 10045, 10075

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 21 2010

Keywords

• nonn
• less

Comments

Intersection of A171697 and A167175. - R. J. Mathar, Mar 29 2010

Examples

			a(1)=1(without prime factors), a(2)=625(=5*5*5*5), a(3)=1715(=5*7*7*7).
		

Crossrefs

Cf. A167175, A171697.

Programs

PARI

isA171995(n)=n>0&!isprime(n)&((n%6==1&!isprime(n-2))||(n%6==5&!isprime(n+2)))&!isprime(bigomega(n))

Extensions

Edited and extended by Charles R Greathouse IV, Mar 29 2010