OFFSET
0,2
LINKS
Max Alekseyev, Table of n, a(n) for n = 0..345
FORMULA
a(n) = A366579(2*n). - Max Alekseyev, Jan 08 2024
MATHEMATICA
EulerPhi[9^Range[0, 20] + 1] (* Paul F. Marrero Romero, Nov 04 2023 *)
PROG
(PARI) {a(n) = eulerphi(9^n+1)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved