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A073639
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Numbers k such that x^k + x + 1 is a primitive polynomial modulo 2.
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6
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2, 3, 4, 6, 7, 15, 22, 60, 63, 127, 153, 471, 532, 865, 900, 1366
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OFFSET
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1,1
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COMMENTS
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Subsequence of A002475, which gives k for which the polynomial x^k + x + 1 is irreducible modulo 2. Term m of A002475 belongs to this sequence iff A046932(m) = 2^m - 1.
Note that a(16) = 1366 = A002475(23). For k = A002475(24) and A002475(25), polynomial x^k + x + 1 is not primitive modulo 2, so a(17) >= A002475(26) = 4495.
The following large terms of A002475 do not belong here: 53484, 62481, 83406, 103468. - Max Alekseyev, Aug 18 2015
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LINKS
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MATHEMATICA
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Select[Range[2, 1000], PrimitivePolynomialQ[x^# + x + 1, 2] &] (* Robert Price, Sep 19 2018 *)
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CROSSREFS
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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STATUS
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approved
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