

A066278


Least solution to cototient[x] = xPhi[x] = n!.


0



2, 4, 10, 36, 168, 1008, 7056, 56448, 470400, 4704000, 51528960, 618347520, 7740902400, 108372633600
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OFFSET

1,1


COMMENTS

a(15) <= 1625589504000. a(16) <= 26009432064000. a(17) <= 442160345088000. [From Donovan Johnson, Feb 05 2010]


LINKS

Table of n, a(n) for n=1..14.


FORMULA

a(n)=Min{x; xA000010(x)=n!} = Min{A051953(x)=A000142(n)}


EXAMPLE

Solutions to xPhi[x]=720 are {1008,1424,1432,1436,1438} of which the smallest is a(6)=1008.


CROSSREFS

Cf. A000010, A051953, A000142, A055487.
Sequence in context: A006396 A192502 A243567 * A210773 A210774 A210775
Adjacent sequences: A066275 A066276 A066277 * A066279 A066280 A066281


KEYWORD

nonn


AUTHOR

Labos Elemer, Dec 10 2001


EXTENSIONS

a(12)a(14) from Donovan Johnson, Feb 05 2010


STATUS

approved



