OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe)
Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).
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
(PARI) is(k) = invphiNum(k) == 11 \\ Amiram Eldar, Nov 17 2024, using Max Alekseyev's invphi.gp
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Apr 18 2001
STATUS
approved