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A109606
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a(n) = number of numbers k with 1 < k < n which are relatively prime to n.
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3
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0, 0, 1, 1, 3, 1, 5, 3, 5, 3, 9, 3, 11, 5, 7, 7, 15, 5, 17, 7, 11, 9, 21, 7, 19, 11, 17, 11, 27, 7, 29, 15, 19, 15, 23, 11, 35, 17, 23, 15, 39, 11, 41, 19, 23, 21, 45, 15, 41, 19, 31, 23, 51, 17, 39, 23, 35, 27, 57, 15, 59, 29, 35, 31, 47, 19, 65, 31, 43, 23, 69, 23, 71, 35, 39, 35
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| a(n) = card({k| k prime to n} setminus {k| k divides n}) # Peter Luschny, Aug 05 2011
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FORMULA
| a(n) = phi(n)-1.
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EXAMPLE
| a(9) = 5 because 2,4,5,7,8 are coprime to 9
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MAPLE
| A109606 := n -> numtheory[phi](n) - 1: # Peter Luschny, Aug 05 2011
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CROSSREFS
| Cf. A000010.
Sequence in context: A143865 A071168 A091926 * A127418 A099550 A099549
Adjacent sequences: A109603 A109604 A109605 * A109607 A109608 A109609
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KEYWORD
| nonn
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AUTHOR
| Andrew Weimholt (andrew(AT)weimholt.com), Jul 31 2005
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EXTENSIONS
| Definition modified by Reinhard Zumkeller, Mar 03 2009
Offset set to 1 in accordance to A000010. Peter Luschny, Aug 05 2011
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