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 A091247 #16 Jan 17 2025 09:14:33 %S A091247 0,0,0,0,1,1,1,0,1,1,1,0,1,0,1,1,1,1,1,0,1,1,1,1,1,0,1,1,1,1,1,0,1,1, %T A091247 1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,0,1,0,1,1,1,1,1,0, %U A091247 1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,1 %N A091247 Characteristic function of A091242: 1 if the n-th GF(2)[X] polynomial is reducible, 0 otherwise. %H A091247 Antti Karttunen, <a href="/A091247/b091247.txt">Table of n, a(n) for n = 0..65537</a> %H A091247 A. Karttunen, <a href="/A091247/a091247.scm.txt">Scheme-program for computing this sequence.</a> %H A091247 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a> %H A091247 <a href="/index/Ge#GF2X">Index entries for sequences operating on GF(2)[X]-polynomials</a> %F A091247 a(n) = A066247(A091203(n)) = A066247(A091205(n)). %o A091247 (PARI) a(n) = if (n<2, 0, ! polisirreducible(Mod(1,2)*Pol(binary(n)))); \\ _Michel Marcus_, Apr 12 2015 %Y A091247 Cf. A066247, A091203, A091205, A091246. %Y A091247 Complementary to A091225. Partial sums give A091245. %K A091247 nonn %O A091247 0,1 %A A091247 _Antti Karttunen_, Jan 03 2004