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Numbers k such that x^k + x^2 + 1 is irreducible over GF(7).
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%I #15 Dec 22 2024 20:12:56

%S 2,3,6,9,18,65,66,287,354,1425,3743,5598

%N Numbers k such that x^k + x^2 + 1 is irreducible over GF(7).

%C No terms == 1 (mod 3), as e.g. 2^k + 2^2 + 1 == 0 mod 7 when k == 1 (mod 3). - _Robert Israel_, Dec 22 2024

%p R:= NULL:

%p for k from 1 to 10000 do

%p if Irreduc(x^k + x^2 + 1) mod 7 then R:= R, k fi

%p od:

%p R; # _Robert Israel_, Dec 22 2024

%Y Cf. A057460, A058857.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Jan 16 2001

%E 2 inserted and more terms from _Robert Israel_, Dec 22 2024