

A066418


Numbers k for which phi(k) + antiphi(k) = k.


3



2, 3, 4, 5, 6, 7, 8, 12, 15, 27, 30, 40, 44, 57, 117, 128, 171, 236, 399, 408, 510, 1623, 3597, 3915, 4616, 4684, 7335, 10197, 10768, 14144, 32768, 39387, 76035, 77097, 106605, 162450, 196080, 219966, 391696
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OFFSET

1,1


COMMENTS

Antiphi(n) (A066452) is the number of numbers coprime to all the antidivisors of n.
See A066272 for definition of antidivisor.


LINKS

Table of n, a(n) for n=1..39.
Jon Perry, Antiphi function [Wayback Machine link]
Jon Perry, The Antidivisor [Cached copy]
Jon Perry, The Antidivisor: Even More AntiDivisors [Cached copy]


EXAMPLE

The antidivisors of 7 are 1, 2, 3 and 5. Therefore of the integer 16, only 1 is coprime to 2, 3 and 5, therefore antiphi(7)=1. phi(7)=6, therefore antiphi(7)+phi(7)=7


CROSSREFS

Cf. A066416, A066417, A058838, A066241, A066272, A066452.
Sequence in context: A321334 A238084 A211202 * A015845 A030702 A305926
Adjacent sequences: A066415 A066416 A066417 * A066419 A066420 A066421


KEYWORD

nonn,more


AUTHOR

Jon Perry, Dec 28 2001


EXTENSIONS

a(21)a(34) from Nathaniel Johnston, Apr 20 2011
a(35)a(39) from Amiram Eldar, Jan 12 2020


STATUS

approved



