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Number of primitive polynomials of degree n over GF(4).
9

%I #12 Jun 17 2024 11:11:13

%S 1,2,4,12,32,120,288,1512,4096,15552,48000,240064,552960,3439800,

%T 9483264,35640000,134217728,673699800,1451188224,9644765256,

%U 23685120000,115605729792,401556013056,1996264531840,4566087106560,26244000000000,89961392102400,356237685227520

%N Number of primitive polynomials of degree n over GF(4).

%H Andrew Howroyd, <a href="/A027695/b027695.txt">Table of n, a(n) for n = 0..150</a>

%p with(numtheory): seq(`if`(n=0, 1, phi(4^n-1)/n), n=0..27);

%t Join[{1}, Array[EulerPhi[4^# - 1]/# &, 30]] (* _Paolo Xausa_, Jun 17 2024 *)

%o (PARI) a(n) = if(n==0, 1, eulerphi(4^n-1)/n) \\ _Andrew Howroyd_, Feb 01 2024

%Y Column k=4 of A369291.

%K nonn

%O 0,2

%A _N. J. A. Sloane_

%E a(24) onwards from _Andrew Howroyd_, Feb 01 2024