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A072209
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Number of primitive roots of those integers with at least one primitive root.
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2
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1, 1, 1, 1, 2, 1, 2, 2, 2, 4, 4, 2, 8, 2, 6, 4, 10, 8, 4, 6, 12, 8, 8, 12, 6, 16, 12, 10, 22, 12, 8, 24, 6, 12, 28, 16, 8, 20, 24, 24, 12, 24, 18, 16, 40, 12, 40
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OFFSET
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1,5
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COMMENTS
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Essentially sequence A046144 with all zero entries deleted.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
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FORMULA
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a(n)=phi[phi{A033948(n)}].
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MATHEMATICA
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Reap[ Do[ If[n == 1, Sow[1], If[ IntegerQ[ PrimitiveRoot[n]], Sow[ EulerPhi[ EulerPhi[n]]]]] , {n, 1, 100}]][[2, 1]] (* From Jean-François Alcover, Feb 24 2012 *)
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CROSSREFS
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Cf. A046144.
Sequence in context: A208216 A208217 A009213 * A060169 A117958 A113401
Adjacent sequences: A072206 A072207 A072208 * A072210 A072211 A072212
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KEYWORD
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nice,nonn
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AUTHOR
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Lekraj Beedassy, Jul 03 2002
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STATUS
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approved
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