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Numbers n such that n-+1 are divisible by exactly 6 primes, counted with multiplicity.
3

%I #4 Sep 23 2019 15:37:20

%S 1889,3079,4591,5023,6175,6641,7649,9881,10961,11501,11935,12689,

%T 13751,14417,15499,15713,16687,18017,18089,18271,19169,19249,19889,

%U 19951

%N Numbers n such that n-+1 are divisible by exactly 6 primes, counted with multiplicity.

%H Harvey P. Dale, <a href="/A157486/b157486.txt">Table of n, a(n) for n = 1..4000</a>

%t q=6;lst={};Do[If[Plus@@Last/@FactorInteger[n-1]==q&&Plus@@Last/@FactorInteger[n+1]==q,AppendTo[lst,n]],{n,9!}];lst

%t Mean/@SequencePosition[PrimeOmega[Range[20000]],{6,_,6}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 23 2019 *)

%Y Cf. A124936, A014612, A157483, A157484, A157485

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Mar 01 2009