A057479 Numbers k such that x^k + x^9 + 1 is irreducible over GF(2).

1, 4, 5, 8, 11, 12, 14, 18, 23, 28, 30, 36, 49, 54, 60, 68, 71, 79, 84, 103, 113, 151, 156, 191, 198, 364, 390, 470, 476, 508, 540, 620, 721, 823, 865, 1135, 1558, 1825, 1950, 4225, 4788, 8100, 12294, 12553, 14686, 18516, 19660, 24470, 30486, 32086, 43908

Offset: 1

Author

Robert G. Wilson v, Sep 27 2000

Keywords

• nonn

Comments

The b-file contains all terms <= 300000. - Lucas A. Brown, Nov 28 2022

Links

• Lucas A. Brown, Table of n, a(n) for n = 1..67
• Lucas A. Brown, Python program.
• Lucas A. Brown, Sage program.

Crossrefs

Cf. A002475.

Programs

Maple

select(n  -> Irreduc(x^n + x^9 + 1) mod 2, [$1..1000]); # Robert Israel, Oct 20 2016

PARI

isok(n) = polisirreducible(Mod(1,2)*(x^n + x^9 + 1)); \\ Michel Marcus, Oct 20 2016

Extensions

a(34)-a(41) from Robert Israel, Oct 20 2016

a(42) from Alois P. Heinz, Oct 20 2016

a(43)-a(67) from Lucas A. Brown, Nov 28 2022