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A227180
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Composite numbers n such that b^(n-1) == 1 (mod n) implies b == -1 or +1 (mod n).
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2
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4, 6, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 27, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 54, 56, 58, 60, 62, 64, 68, 72, 74, 78, 80, 81, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 114, 116, 118, 120, 122, 126, 128, 132, 134, 136, 138, 140, 142, 144, 146, 150, 152, 156, 158, 160, 162, 164, 166, 168, 170
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OFFSET
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1,1
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COMMENTS
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The sequence is the union of A111305 with {3^k | k > 1}.
The composite numbers not in this sequence are the Fermat pseudoprimes A181780.
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LINKS
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MATHEMATICA
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FQ[k_]:= Block[{}, GCD[EulerPhi[k], k-1]==1||IntegerQ[Log[3, k]]]; Select[Range[4, 170], FQ]
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PROG
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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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