A060671 Numbers n such that phi(x) = n has exactly 8 solutions.

36, 64, 176, 200, 224, 280, 324, 464, 520, 888, 920, 1184, 1368, 1400, 1520, 1696, 1720, 1904, 1960, 2040, 2096, 2120, 2256, 2392, 2600, 2656, 2712, 2752, 2864, 2944, 2960, 2968, 2976, 2988, 3104, 3276, 3300, 3408, 3616, 3640, 3792, 3800, 3816, 3824, 3880

Offset

1,1

Links

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

Example

36 = phi(37) = phi(57) = phi(63) = phi(74) = phi(76) = phi(108) = phi(114) = phi(126).

Mathematica

a = Table[ 0, {5000} ]; Do[ p = EulerPhi[ n ]; If[ p < 5001, a[ [ p ] ]++ ], {n, 1, 25000} ]; Select[ Range[ 5000 ], a[ [ # ] ] == 8 & ]

Prog

(PARI) is(n)=sum(i=1, n, eulerphi(i)==n)==8 \\ Charles R Greathouse IV, Mar 03 2014

Crossrefs

Cf. A007366, A007367.

Sequence in context: A343293 A326666 A272190 * A269499 A074315 A240520

Adjacent sequences: A060668 A060669 A060670 * A060672 A060673 A060674

Keyword

nonn

Author

Robert G. Wilson v, Apr 18 2001

Status

approved