This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A058857 #20 Apr 17 2020 07:41:00 %S A058857 0,1,3,4,9,33,52,177,1042,2799,5950,8595,19438 %N A058857 Numbers n such that the trinomial x^n + x + 1 is irreducible over GF(7). %C A058857 No other terms <= 4000. - _Eric M. Schmidt_, Feb 10 2014 %C A058857 Next term > 2*10^4. [_Joerg Arndt_, Mar 02 2016] %o A058857 (Sage) def isA058857(n) : x = GF(7)['x'].0; return (x^n + x + 1).is_irreducible() # _Eric M. Schmidt_, Feb 10 2014 %o A058857 (PARI) isok(n) = polisirreducible(Mod(1, 7)*(x^n + x + 1)); \\ _Michel Marcus_, Feb 11 2014 %Y A058857 Cf. A002475 (GF(2)), A058334 (GF(5)). %K A058857 nonn,more %O A058857 1,3 %A A058857 _Robert G. Wilson v_, Jan 05 2001 %E A058857 a(1), a(2) and a(10) from _Eric M. Schmidt_, Feb 10 2014 %E A058857 a(11) - a(13) from _Joerg Arndt_, Mar 02 2016