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

1,1

Comments

There are 106 of these numbers below 10^5.

Links

Table of n, a(n) for n=1..41.

Example

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

Mathematica

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

Crossrefs

Cf. A014612.

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

Sequence in context: A167597 A138636 A075281 * A333869 A257768 A007371

Adjacent sequences: A171176 A171177 A171178 * A171180 A171181 A171182

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Dec 04 2009

Status

approved