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A264164
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3-smooth numbers whose number of divisors is not 3-smooth.
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2
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16, 48, 64, 81, 144, 162, 192, 324, 432, 512, 576, 648, 729, 1024, 1296, 1458, 1536, 1728, 2592, 2916, 3072, 3888, 4096, 4608, 5184, 5832, 8192, 9216, 10368, 11664, 12288, 13824, 15552, 16384, 19683, 20736, 23328, 24576, 27648, 34992, 36864, 39366, 41472
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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but A003586(38) = 768 = 2^8*3 is not a term, as A000005(768) = 18 = 2*3^2.
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MATHEMATICA
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smQ[n_] := n == Times @@ ({2, 3}^IntegerExponent[n, {2, 3}]);
seq[max_] := Sort@ Flatten@ Table[If[smQ[i + 1] && smQ[j + 1], Nothing, 2^i * 3^j], {i, 0 , Log2[max]}, {j, 0, Log[3, max/2^i]}]; seq[42000] (* Amiram Eldar, Sep 03 2023 *)
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PROG
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(Haskell)
a264164 n = a264164_list !! (n-1)
a264164_list = filter ((== 0) . a065333 . a000005') a003586_list
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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