OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..980 from Paul Tek)
Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).
MATHEMATICA
Flatten@ Position[#, 0] &@ Table[k = n + 1; While[And[k <= 2 n + 1, EulerPhi@ k != EulerPhi@ n], k++]; Boole[k < 2 n + 1] k, {n, 400}] (* Michael De Vlieger, Dec 31 2016 *)
PROG
(PARI) is(k) = #select(x -> x>k, invphi(eulerphi(k))) == 0; \\ Amiram Eldar, Nov 12 2024, using Max Alekseyev's invphi.gp
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Vladeta Jovovic, Jan 12 2002
EXTENSIONS
Offset corrected by Paul Tek, Sep 25 2015
Definition clarified by Alonso del Arte, Dec 31 2016
STATUS
approved