OFFSET
1,1
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
EXAMPLE
160 = phi(187) = phi(205) = phi(328) = phi(352) = phi(374) = phi(400) = phi(410) = phi(440) = phi(492) = phi(528) = phi(600) = phi(660).
MATHEMATICA
a = Table[ 0, {15000} ]; Do[ p = EulerPhi[ n ]; If[ p < 15001, a[ [ p ] ]++ ], {n, 1, 60000} ]; Select[ Range[ 15000 ], a[ [ # ] ] == 12 & ]
Union[Transpose[Select[Tally[EulerPhi[Range[100000]]], #[[2]]==12&]][[1]]] (* Harvey P. Dale, Oct 05 2015 *)
PROG
(PARI) is(n)=sum(i=1, n, eulerphi(i)==n)==12 \\ Charles R Greathouse IV, Mar 03 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Apr 18 2001
STATUS
approved