The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A166987 Members of A143610 for which both neighbors are squarefree. 0
 72, 108, 200, 392, 500, 968, 1352, 1372, 4232, 7688, 8788, 13448, 14792, 17672, 19652, 27436, 27848, 35912, 48668, 49928, 55112, 75272, 81608, 84872, 97556, 102152, 119164, 137288, 150152, 154568, 177608, 182408, 197192, 202612, 223112 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers of the form n=p^2*q^3 where p and q are two different primes and where n+1 and n-1 are both in A005117. LINKS MATHEMATICA f[n_]:=Last/@FactorInteger[n]=={2, 3}||Last/@FactorInteger[n]=={3, 2}; << NumberTheory`NumberTheoryFunctions` lst={}; Do[If[f[n], If[SquareFreeQ[n-1]&&SquareFreeQ[n+1], AppendTo[lst, n]]], {n, 3*9!}]; lst CROSSREFS Cf. A067874. Sequence in context: A052486 A114128 A143610 * A251124 A169644 A078667 Adjacent sequences:  A166984 A166985 A166986 * A166988 A166989 A166990 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Oct 26 2009 EXTENSIONS Definition narrowed by R. J. Mathar, Oct 28 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 30 12:21 EDT 2020. Contains 337439 sequences. (Running on oeis4.)