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First primitive GF(2)[X] polynomials of degree n with at most 5 terms, X^n suppressed.
4

%I #11 May 06 2022 13:13:51

%S 1,3,3,3,5,3,3,29,17,9,5,83,27,43,3,45,9,39,39,9,5,3,33,27,9,71,39,9,

%T 5,83,9,197,83,281,5,387,83

%N First primitive GF(2)[X] polynomials of degree n with at most 5 terms, X^n suppressed.

%C More precisely: minimum value for X=2 of GF(2)[X] polynomials P[X] with at most 4 terms such that X^n+P[X] is primitive. Applications include maximum-length linear feedback shift registers with efficient implementation in both hardware and software. The limitation of the number of terms occurs first for a(32), which is 197 representing X^7+X^6+X^2+1, rather than 175 representing X^7+X^5+X^3+X^2+X^1+1. Proof is needed that there exists a primitive GF(2)[X] polynomial P[X] of degree n and at most 5 terms for all positive n.

%H <a href="/index/Ge#GF2X">Index entries for sequences operating on GF(2)[X]-polynomials</a>

%e a(11)=5, or 101 in binary, representing the GF(2)[X] polynomial X^2+1, because X^11+X^2+1 has no more than 5 terms and X is primitive, contrary to X^11, X^11+1, X^11+X^1, X^11+X^1+1 and X^11+X^2.

%Y 2^n+a(n) belongs to A091250. A132449(n) = a(n)+2^n and gives the corresponding primitive polynomial. Cf. A132448 (similar, with no restriction on number of terms). Cf. A132452 (similar, with restriction to exactly 5 terms).

%K nonn,more

%O 1,2

%A _Francois R. Grieu_, Aug 22 2007