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A060673 Numbers n such that phi(x) = n has exactly 10 solutions. 1
24, 80, 180, 256, 264, 828, 1188, 1640, 1968, 2024, 2368, 2544, 2720, 2772, 2904, 3036, 3136, 3144, 3328, 3392, 3420, 4192, 4392, 4464, 4600, 5000, 5312, 5504, 5508, 5688, 5728, 5796, 5800, 6208, 6228, 6732, 6888, 7000, 7232, 7740, 7956, 8388, 8576, 9088 (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

24 = phi(35) = phi(39) = phi(45) = phi(52) = phi(56) = phi(70) = phi(72) = phi(78) = phi(84) = phi(90).

MATHEMATICA

a = Table[ 0, {10000} ]; Do[ p = EulerPhi[ n ]; If[ p < 10001, a[ [ p ] ]++ ], {n, 1, 35000} ]; Select[ Range[ 10000 ], a[ [ # ] ] == 10 & ]

PROG

(PARI) is(n)=sum(i=1, n, eulerphi(i)==n)==10 \\ Charles R Greathouse IV, Mar 03 2014

CROSSREFS

Cf. A007366, A007367.

Sequence in context: A143839 A114818 A190102 * A167561 A211575 A211583

Adjacent sequences:  A060670 A060671 A060672 * A060674 A060675 A060676

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Apr 18 2001

STATUS

approved

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Last modified September 25 17:49 EDT 2022. Contains 356986 sequences. (Running on oeis4.)