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A060674 Numbers n such that phi(x) = n has exactly 11 solutions. 2
48, 512, 540, 1000, 1836, 2136, 2176, 2320, 2340, 3216, 3648, 3936, 4284, 4352, 4356, 4784, 5088, 5640, 5936, 6216, 6576, 6816, 7120, 7224, 7280, 7752, 8100, 8184, 8496, 8520, 8760, 9040, 9296, 9660, 9680, 9900, 9996, 10332, 10860, 11640, 11680, 11844 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

EXAMPLE

48 = phi(65) = phi(104) = phi(105) = phi(112) = phi(130) = phi(140) = phi(144) = phi(156) = phi(168) = phi(180) = phi(210).

MATHEMATICA

a = Table[ 0, {12500} ]; Do[ p = EulerPhi[ n ]; If[ p < 12501, a[ [ p ] ]++ ], {n, 1, 50000} ]; Select[ Range[ 12500 ], a[ [ # ] ] == 11 & ]

PROG

(PARI) is(n)=sum(i=1, n, eulerphi(i)==n)==11 \\ Charles R Greathouse IV, Mar 03 2014

CROSSREFS

Cf. A007366, A007367.

Sequence in context: A198398 A211149 A034778 * A233165 A247743 A189346

Adjacent sequences:  A060671 A060672 A060673 * A060675 A060676 A060677

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Apr 18 2001

STATUS

approved

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Last modified May 16 12:54 EDT 2021. Contains 343947 sequences. (Running on oeis4.)