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Search: id:A010554
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| A010554 |
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phi(phi(n)), where phi is Euler totient function. |
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+0
12
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| 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 4, 2, 4, 2, 4, 4, 8, 2, 6, 4, 4, 4, 10, 4, 8, 4, 6, 4, 12, 4, 8, 8, 8, 8, 8, 4, 12, 6, 8, 8, 16, 4, 12, 8, 8, 10, 22, 8, 12, 8, 16, 8, 24, 6, 16, 8, 12, 12, 28, 8, 16, 8, 12, 16, 16, 8, 20, 16, 20, 8, 24, 8
(list; graph; listen)
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OFFSET
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1,5
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 840.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
S. R. Finch, Idempotents and Nilpotents Modulo n (arXiv:math.NT/0605019)
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MAPLE
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with(numtheory): f := n->phi(phi(n));
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MATHEMATICA
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Table[EulerPhi[EulerPhi[n]], {n, 0, 200}] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 10 2009]
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CROSSREFS
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Cf. A000010.
Sequence in context: A077197 A117173 A103858 this_sequence A062610 A025801 A140426
Adjacent sequences: A010551 A010552 A010553 this_sequence A010555 A010556 A010557
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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