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A106840
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Numbers m such that both m and m+1 have odd part of the form 4*k+1.
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2
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1, 4, 8, 9, 16, 17, 20, 25, 32, 33, 36, 40, 41, 49, 52, 57, 64, 65, 68, 72, 73, 80, 81, 84, 89, 97, 100, 104, 105, 113, 116, 121, 128, 129, 132, 136, 137, 144, 145, 148, 153, 160, 161, 164, 168, 169, 177, 180, 185, 193, 196, 200, 201, 208, 209, 212, 217, 225
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OFFSET
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1,2
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COMMENTS
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The asymptotic density of this sequence is 1/4. (End)
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LINKS
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EXAMPLE
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20/4 = 5 == 1 (mod 4) and also 21 == 1 (mod 4), therefore 20 is in the sequence.
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MATHEMATICA
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f[n_] := Mod[n / 2^IntegerExponent[n, 2] - 1, 4]; SequencePosition[Array[f, 250], {0, 0}][[;; , 1]] (* Amiram Eldar, Sep 14 2024 *)
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CROSSREFS
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KEYWORD
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nonn,changed
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AUTHOR
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STATUS
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approved
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