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 A260427 #15 Feb 06 2023 05:02:09
%S A260427 5,17,23,29,43,53,69,71,77,79,81,83,89,101,107,113,121,127,139,149,
%T A260427 151,163,169,173,179,181,197,199,205,209,223,227,233,251,257,261,263,
%U A260427 265,269,271,275,277,281,289,293,295,305,307,311,317,321,323,327,329,331,337,339,347,349,353,359,367,373,377,383,389,401
%N A260427 Binary codes for polynomials (with coefficients 0 or 1) that are irreducible over Q, but reducible over GF(2).
%H A260427 Antti Karttunen, <a href="/A260427/b260427.txt">Table of n, a(n) for n = 1..16972</a>
%t A260427 okQ[n_] := Module[{id, pol, x}, id = IntegerDigits[n, 2] // Reverse; pol = id.x^Range[0, Length[id] - 1]; IrreduciblePolynomialQ[pol] && !IrreduciblePolynomialQ[pol, Modulus -> 2]];
%t A260427 Select[Range[1000], okQ] (* _Jean-François Alcover_, Feb 06 2023 *)
%o A260427 (PARI)
%o A260427 isA260427(n) = (polisirreducible( Pol(binary(n)) ) && !polisirreducible(Pol(binary(n))*Mod(1, 2)));
%o A260427 n = 0; i = 0; while(n < 65537, n++; if(isA260427(n), i++; write("b260427.txt", i, " ", n)));
%Y A260427 Intersection of A091242 and A206074.
%Y A260427 Subsequence: A260428.
%Y A260427 Cf. also A260426, A206075.
%K A260427 nonn
%O A260427 1,1
%A A260427 _Antti Karttunen_, Jul 26 2015