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A305678 Solutions x of uphi(x)/x = 2/3, where uphi is the unitary phi function (A047994). 4
3, 36, 504, 720, 1404, 19656, 28080, 44640, 181440, 195840, 1740960, 7637760, 46085760, 65862720, 105960960, 12884705280, 16729130880, 22826833920, 38463828480, 502503505920, 890246522880, 3377622411509760, 131727274048880640, 55340232208243752960, 2158269056121506365440 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Apparently, these is a single x, 6, such that uphi(x)/x = 1/3.

LINKS

Table of n, a(n) for n=1..25.

Tomohiro Yamada, An analog of perfect numbers involving the unitary totient function, arXiv:1806.00647 [math.NT], 2018.

EXAMPLE

uphi(3) = 2 so uphi(3)/3 = 2/3;

uphi(36) = 24 so uphi(36)/36 = 2/3.

PROG

(PARI) solve_uphi(2, 3, 10^40) \\ see A030163

CROSSREFS

Cf. A047994 (uphi), A030163 (uphi(x)/x = 1/2).

Sequence in context: A199258 A262465 A322491 * A233196 A245114 A276018

Adjacent sequences:  A305675 A305676 A305677 * A305679 A305680 A305681

KEYWORD

nonn

AUTHOR

Michel Marcus, Jun 08 2018

STATUS

approved

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Last modified April 8 08:04 EDT 2020. Contains 333313 sequences. (Running on oeis4.)