%I #4 Jun 05 2016 14:36:47
%S 645,741,805,987,1035,1065,1105,1221,1275,1309,1310,1463,1495,1581,
%T 1749,1885,1886,1925,1989,2014,2015,2109,2135,2211,2255,2261,2289,
%U 2295,2331,2355,2365,2379,2409,2465,2485,2541,2584,2585,2665,2666,2667,2679,2685
%N Numbers n such that n and n+-1 have 3 or more distinct prime factors.
%t f[n_]:=Length[FactorInteger[n]]; lst={};Do[If[f[n]>=3&&f[n-1]>=3&&f[n+1]>=3,AppendTo[lst,n]],{n,7!}];lst
%t Mean/@SequencePosition[Table[If[PrimeNu[n]>2,1,0],{n,2700}],{1,1,1}] (* The program uses the SequencePosition function from Mathematica version 10 *) (* _Harvey P. Dale_, Jun 05 2016 *)
%Y Cf. A140077
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Dec 01 2009
%E Definition clarified by _Harvey P. Dale_, Jun 05 2016