A168628 Numbers n such that n and n+-1 have 4 distinct prime factors.

37961, 44485, 45695, 50141, 51429, 55131, 55385, 61335, 63365, 64295, 67165, 68265, 68475, 70005, 70091, 71709, 72709, 76153, 80445, 81549, 81719, 82041, 84435, 85491, 86241, 90364, 95381, 97383, 98021, 99085, 99385, 99429, 99789, 100165, 100491, 100595

Offset

1,1

Links

Table of n, a(n) for n=1..36.

Mathematica

f[n_]:=Length[FactorInteger[n]]; lst={}; Do[If[f[n]>=4&&f[n-1]>=4&&f[n+1]>=4, AppendTo[lst, n]], {n, 9!}]; lst
SequencePosition[PrimeNu[Range[110000]], {4, 4, 4}][[All, 1]]+1 (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 27 2018 *)

Crossrefs

Cf. A140077, A140078, A168626

Sequence in context: A172425 A224906 A364309 * A178286 A187938 A235185

Adjacent sequences: A168625 A168626 A168627 * A168629 A168630 A168631

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Dec 01 2009

Extensions

Corrected and extended by Harvey P. Dale, Apr 27 2018

Status

approved