OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..388
MATHEMATICA
EulerPhi[7^Range[30] - 1] (* Wesley Ivan Hurt, Oct 15 2023 *)
PROG
(PARI) {a(n) = eulerphi(7^n-1)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved