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 A272486 #33 Apr 29 2019 09:49:39
%S A272486 8,13,16,19,24,26,27,32,37,38,40,42,43,45,48,50,51,53,54,56,59,61,64,
%T A272486 66,67,69,70,72,75,77,78,80,82,83,85,88,90,91,96,99,101,104,107,109,
%U A272486 110,112,114,115,116,117,120,122,125,126,128,131,133,136,138,139
%N A272486 Numbers n > 1 such that the polynomial x^(n-k)*(x+1)^k+1 over GF(2) is reducible for all k from 1 to n-1.
%C A272486 If n = p is an odd prime, the sequence appears coincide with A057749. Is this true, and if so, why?
%C A272486 More generally, the sequence appears the same as the set complement of A073571 (minus {1}). Again, if true, why? [This is not correct. E.g., the terms 42, 54, 66, 90, and 110 are in both sequences. _Joerg Arndt_, Apr 29 2019]
%t A272486 ok[n_] := {} == Quiet@ Select[Range[n-1], IrreduciblePolynomialQ[ x^(n-#) * (x+1)^# + 1, Modulus -> 2] &, 1]; Select[Range[2, 140], ok] (* _Giovanni Resta_, May 02 2016 *)
%o A272486 (PARI) isok(n) = if (n<=1, 0, for (k=1, n-1, if (polisirreducible(Mod(1,2)*(x^(n-k)*(x+1)^k+1)), return(0));); 1;); \\ _Michel Marcus_, May 02 2016
%Y A272486 Cf. A057749, A073571.
%K A272486 nonn
%O A272486 1,1
%A A272486 _Luis H. Gallardo_, May 01 2016
%E A272486 a(41)-a(60) from _Giovanni Resta_, May 02 2016