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A090086
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Smallest [odd and even] pseudoprimes to base n, not necessarily exceeding n. See A007535.
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5
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4, 341, 91, 15, 4, 35, 6, 9, 4, 9, 10, 65, 4, 15, 14, 15, 4, 25, 6, 21, 4, 21, 22, 25, 4, 9, 26, 9, 4, 49, 6, 25, 4, 15, 9, 35, 4, 39, 38, 39, 4, 205, 6, 9, 4, 9, 46, 49, 4, 21, 10, 51, 4, 55, 6, 15, 4, 57, 15, 341, 4, 9, 62, 9, 4, 65, 6, 25, 4, 69, 9, 85, 4, 15, 74, 15, 4, 77, 6, 9, 4, 9, 21
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n)=Min{x; Mod[ -1+n^(x-1), x]=0}
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EXAMPLE
| at n=4k+1, a[n]=4
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MATHEMATICA
| Table[fla=1; Do[s=Mod[ -1+a^(n-1), n]; If[Equal[s, 0]&&!PrimeQ[n]&&Greater[n, 1]&&Equal[fla, 1], Print[{n, a, GCD[n, a]}]; fla=0], {n, 1, 342}], {a, 2, 256}]
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CROSSREFS
| Cf. A007535.
Sequence in context: A135442 A086895 A173367 * A007535 A000783 A098654
Adjacent sequences: A090083 A090084 A090085 * A090087 A090088 A090089
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Nov 25 2003
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