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 A027385 Number of primitive polynomials of degree n over GF(3). 10
 1, 2, 4, 8, 22, 48, 156, 320, 1008, 2640, 7700, 13824, 61320, 170352, 401280, 983040, 3796100, 7838208, 30566592, 62304000, 229686912, 670824000, 2003046356, 3583180800, 15403487000, 48881851200, 128672022528, 314657860608, 1163185915872, 2340264960000, 9947788640064 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Second row of the array T(n,k) = phi(p^k-1)/k, p=prime(n), which starts 1,  1,   2,    2,      6,       6,       18,        16, ...    A011260 1,  2,   4,    8,     22,      48,      156,       320, ...    here 2,  4,  20,   48,    280,     720,     5580,     14976, ...    A027741 2,  8,  36,  160,   1120,    6048,    37856,    192000, ...    A027743 4, 16, 144,  960,  12880,   62208,  1087632,   7027200, ...    A319166 4, 24, 240, 1536,  24752,  224640,  2988024,  21934080, ... 8, 48, 816, 5376, 141984, 1057536, 29309904, 224501760, ... - R. J. Mathar, Aug 24 2011 From Joerg Arndt, Oct 03 2012: (Start) Number of base-3, length-n Lyndon words w such that gcd(w, 3^n-1)==1 (where w is interpreted as a radix-3 number); replacing 3 by any prime p gives the analogous statement for GF(p). The statement above is the consequence of the following. Let p be a prime and g be a generator of GF(p^n). If w is a base-p, length-n Lyndon word then f=g^w (where w is interpreted as a radix-p number) has an irreducible characteristic polynomial C (over GF(p)) and, if gcd(w,p^n-1)==1 then C is primitive. (End) LINKS Vaclav Kotesovec, Table of n, a(n) for n = 1..200 (terms 1..100 from Seiichi Manyama) Eric W. Weisstein, MathWorld: Totient Function Wikipedia, Euler's totient function MAPLE A027385 := proc(n) numtheory[phi](3^n-1)/n; end proc: MATHEMATICA Table[EulerPhi[3^n - 1]/n, {n, 1, 30}] (* Vaclav Kotesovec, Nov 23 2017 *) PROG (PARI) a(n) = eulerphi(3^n-1)/n; /* Joerg Arndt, Aug 25 2011 */ CROSSREFS Sequence in context: A027713 A155765 A217975 * A158324 A002075 A293912 Adjacent sequences:  A027382 A027383 A027384 * A027386 A027387 A027388 KEYWORD nonn AUTHOR STATUS approved

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Last modified February 21 04:18 EST 2019. Contains 320371 sequences. (Running on oeis4.)