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A037171
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Numbers n such that phi(n) = pi(n), i.e. A000010(n) = A000720(n).
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13
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OFFSET
| 1,1
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COMMENTS
| David W. Wilson (davidwwilson(AT)comcast.net) and Jeffrey Shallit showed that 90 is the last term.
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REFERENCES
| D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 11.
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EXAMPLE
| phi(10)=4, pi(10)=4.
a(1)=2 since k=2 is the lowest index for which A000720(n) = A000010(n), i.e. EulerPhi(n)=PrimePi(n) [M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Mar 30 2007]
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MAPLE
| select(x->numtheory[phi](x)=numtheory[pi](x), [$1..999]); # M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Mar 30 2007
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PROG
| (PARI:) for(n=1, 1e5, if(primepi(n)==eulerphi(n), print(n))) /* M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Mar 30 2007 */
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CROSSREFS
| Cf. A037228, A000720, A000010.
Sequence in context: A051783 A033083 A005542 * A186417 A114854 A127279
Adjacent sequences: A037168 A037169 A037170 * A037172 A037173 A037174
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KEYWORD
| easy,nonn,fini,full
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AUTHOR
| Naohiro Nomoto (6284968128(AT)geocities.co.jp)
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