OFFSET
1,1
LINKS
Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems: invphi.gp, 2005-2009.
PROG
(PARI) a(n) = {my(v = invphi(n), m = if (#v, vecmax(v), n)); vecmax(select(x->(Mod(eulerphi(x), x) == n), [1..m])); } \\ Michel Marcus, Feb 22 2021; needs invphi
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 24 2002
EXTENSIONS
More terms from Michel Marcus, Feb 22 2021
STATUS
approved