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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The asymptotic density of this sequence is 15/(2*Pi^2) (A323669). - Amiram Eldar, May 10 2022 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 MATHEMATICA Union[Join[{9, 18}, Select[Range[100], (e = IntegerExponent[#, 2]) <= 3 && SquareFreeQ[#/2^e] &]]] (* Amiram Eldar, May 10 2022 *) CROSSREFS Cf. A005117, A121684, A323669. Sequence in context: A337138 A023757 A115105 * A028261 A119675 A253781 Adjacent sequences:  A121173 A121174 A121175 * A121177 A121178 A121179 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 13 2006 STATUS approved

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Last modified August 9 18:55 EDT 2022. Contains 356026 sequences. (Running on oeis4.)