A171179 Numbers that are divisible by exactly 3 primes (counted with multiplicity) and sandwiched between primes.

12, 18, 30, 42, 102, 138, 282, 618, 642, 822, 1698, 1878, 2082, 2238, 2382, 2658, 2802, 3462, 3558, 3918, 4638, 4722, 5442, 6198, 6702, 8538, 8598, 9678, 10938, 12162, 12378, 12822, 12918, 13218, 13722, 13758, 13998, 14082, 16062, 17418, 19542

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Dec 04 2009

Keywords

• nonn

Comments

There are 106 of these numbers below 10^5.

Examples

			12 is a term: 12 = 2*2*3, and 11 and 13 primes.
		

Crossrefs

Cf. A014612.

Equals 6*A060212. - Zak Seidov and Esko Ranta, Dec 06 2009

Programs

Mathematica

Select[Range[9! ],Plus@@Last/@FactorInteger[ # ]==3&&PrimeQ[ #-1]&&PrimeQ[ #+1]&]