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A121176
Union of {8, 9, 18}, S, 2S and 4S, where S = squarefree numbers (A005117).
3
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 91, 92
OFFSET
1,2
COMMENTS
The asymptotic density of this sequence is 15/(2*Pi^2) (A323669). - Amiram Eldar, May 10 2022
LINKS
MATHEMATICA
Union[Join[{9, 18}, Select[Range[100], (e = IntegerExponent[#, 2]) <= 3 && SquareFreeQ[#/2^e] &]]] (* Amiram Eldar, May 10 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 13 2006
STATUS
approved