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Non-multiples of Fermat numbers 2^(2^n)+1.
4

%I #10 Aug 16 2019 00:18:38

%S 1,2,4,7,8,11,13,14,16,19,22,23,26,28,29,31,32,37,38,41,43,44,46,47,

%T 49,52,53,56,58,59,61,62,64,67,71,73,74,76,77,79,82,83,86,88,89,91,92,

%U 94,97,98,101,103,104,106,107,109,112,113,116,118,121,122,124,127,128,131

%N Non-multiples of Fermat numbers 2^(2^n)+1.

%C Complement of A080307. A080307 and A080308 each comprise one-half of the integers; see A080307.

%C It appears that the first 128 terms of this sequence constitute all of the primitive elements of GF(256) if each term is the exponent of the minimum primitive element for the irreducible polynomial splitting GF(2). For example, when GF(2) is split by F(x) = x^8 + x^4 + x^3 + x + 1, the minimum primitive element is a = x + 1. Then the primitive elements of the finite field are a^1, a^2, a^4, a^7, ... - _Cody Planteen_, Jul 27 2019

%H C. Planteen, <a href="https://codyplanteen.com/assets/rs/gf256_prim.pdf">Primitive elements and irreducible polynomials of GF(256)</a>

%Y Cf. A000215, A080307.

%K easy,nonn

%O 1,2

%A _Matthew Vandermast_, Feb 16 2003