A085706 Squarefree numbers sandwiched between two brilliant numbers.

5, 870, 1158, 24882, 35238, 37770, 39270, 46002, 47262, 48930, 51810, 55482, 59910, 62430, 65622, 69870, 76458, 85542, 88638, 90942, 91338, 91362, 91830, 93018, 93882, 94362, 95298, 97638, 98070, 99510, 101262, 103602, 112038, 116022, 118230

Offset

1,1

Links

Table of n, a(n) for n=1..35.

Example

a(3)=1158 because it is squarefree and 1157 = 13*89 is brilliant as is
1159 = 19*61.

Mathematica

sfnQ[{a_, b_, c_}]:=Module[{a1=FactorInteger[a][[All, 1]], c1= FactorInteger[ c][[All, 1]]}, Length[a1]==Length[c1]==2&&PrimeOmega[a]== PrimeOmega[c] == 2&&IntegerLength[a1[[1]]]==IntegerLength[a1[[2]]]&&IntegerLength[ c1[[1]]] == IntegerLength[c1[[2]]]&&SquareFreeQ[b]]; Join[{5}, Select[ Partition[Range[120000], 3, 1], sfnQ][[All, 2]]] (* Harvey P. Dale, Nov 26 2016 *)

Crossrefs

Cf. A078972.

Sequence in context: A198402 A214450 A332185 * A190350 A135084 A206356

Adjacent sequences: A085703 A085704 A085705 * A085707 A085708 A085709

Keyword

nonn

Author

Jason Earls, Jul 18 2003

Status

approved