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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
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.
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: A375143 A375073 A143610 * A339940 A251124 A169644
KEYWORD
nonn
AUTHOR
EXTENSIONS
Definition narrowed by R. J. Mathar, Oct 28 2009
STATUS
approved