%I #12 Jun 17 2024 18:36:11
%S 1,4,16,96,640,5280,27648,340704,1966080,15676416,124608000,
%T 1341648000,7166361600,97763702400,629315721216,4680529920000,
%U 42316647628800,483414202656000,2396062681399296,35513562609100800,211942058803200000,2006922093666287616,16837843397760000000
%N Number of primitive polynomials of degree n over GF(9).
%H Andrew Howroyd, <a href="/A027745/b027745.txt">Table of n, a(n) for n = 0..100</a>
%p with(numtheory): seq(`if`(n=0, 1, phi(9^n-1)/n), n=0..22);
%t Join[{1}, Array[EulerPhi[9^# - 1]/# &, 25]] (* _Paolo Xausa_, Jun 17 2024 *)
%o (PARI) a(n) = if(n==0, 1, eulerphi(9^n-1)/n) \\ _Andrew Howroyd_, Feb 01 2024
%Y Column k=9 of A369291.
%K nonn
%O 0,2
%A _N. J. A. Sloane_
%E a(20) onwards from _Andrew Howroyd_, Feb 01 2024