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A048864
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Number of nonprime numbers (composites and 1) in the reduced residue system of n.
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11
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1, 1, 1, 1, 2, 1, 3, 1, 3, 2, 6, 1, 7, 2, 4, 3, 10, 1, 11, 2, 6, 4, 14, 1, 12, 5, 10, 5, 19, 1, 20, 6, 11, 7, 15, 3, 25, 8, 14, 6, 28, 2, 29, 8, 12, 10, 32, 3, 28, 7, 19, 11, 37, 4, 26, 10, 22, 14, 42, 2, 43, 14, 20, 15, 32, 5, 48, 15, 27, 8, 51, 6, 52, 17, 21, 17, 41, 6, 57, 12, 33, 20
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| Differs from A039776 at n = 20, 21, ...
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FORMULA
| A048864(n) = A036997(n) + 1. - Peter Luschny, Oct 22, 2010.
a(n) = A000010(n) -( A000720(n)-A001221(n) ).
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EXAMPLE
| At n=100, phi(100) = 40, phi(100)-( Pi(100)-A001221(100) )=17, thus a(100) = 17
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MAPLE
| A048864 := n -> nops(select(k->gcd(k, n)=1, remove(isprime, [$1..n]))); [From Peter Luschny (peter(AT)luschny.de), Oct 22 2010]
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CROSSREFS
| Cf. A039776, A000010, A000720, A001221.
Sequence in context: A046073 A162912 A039776 * A003139 A145652 A111248
Adjacent sequences: A048861 A048862 A048863 * A048865 A048866 A048867
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu)
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EXTENSIONS
| Converted second formula to an equation, added commas to the example - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 23 2010
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