A058857 -id:A058857 - cp's OEIS frontend

0, 1, 2, 3, 7, 18, 22, 27, 31, 78, 94, 115, 171, 402, 438, 507, 1363, 1467, 2263, 2283, 3627, 9247, 9955

Offset: 1

Robert G. Wilson v, Dec 13 2000

No other n < 4400. - Michael Somos, Mar 12 2007

Next term > 10^4. [Joerg Arndt, Mar 02 2016]

Cf. A002475 (GF(2)), A058857 (GF(7)).

isok(n) = polisirreducible(Mod(1, 5)*(x^n + x + 1)); \\ Michel Marcus, Feb 11 2014

P. = GF(5)[]
for n in range(0, 10000):
       if (x^n+x+1).is_irreducible():
           print(n)
# Joerg Arndt, Mar 02 2016

a(1) and a(2) from Eric M. Schmidt, Feb 10 2014

a(22) and a(23) from Joerg Arndt, Mar 02 2016

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

Offset: 1

Robert G. Wilson v, Jan 16 2001

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

R:= NULL:
for k from 1 to 10000 do
 if Irreduc(x^k + x^2 + 1) mod 7 then R:= R, k fi
od:
R; # Robert Israel, Dec 22 2024

2 inserted and more terms from Robert Israel, Dec 22 2024

cp's OEIS Frontend