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 A091221 #12 Oct 11 2024 13:10:10 %S A091221 0,1,1,1,1,2,1,1,2,2,1,2,1,2,1,1,1,3,1,2,1,2,2,2,1,2,2,2,2,2,1,1,2,2, %T A091221 2,3,1,2,2,2,1,2,2,2,2,3,1,2,2,2,1,2,2,3,1,2,2,3,1,2,1,2,2,1,2,3,1,2, %U A091221 1,3,2,3,1,2,2,2,2,3,2,2,1,2,3,2,1,3,1,2,2,3,1,3,2,2,2,2,1,3,2,2,3,2 %N A091221 Number of distinct irreducible polynomials dividing n-th GF(2)[X]-polynomial. %H A091221 Robert Israel, <a href="/A091221/b091221.txt">Table of n, a(n) for n = 1..10000</a> %H A091221 A. Karttunen, <a href="/A091247/a091247.scm.txt">Scheme-program for computing this sequence.</a> %H A091221 <a href="/index/Ge#GF2X">Index entries for sequences operating on GF(2)[X]-polynomials</a> %p A091221 f:= proc(n) local L,P,R,i; %p A091221 L:= convert(n,base,2); %p A091221 P:= add(L[i]*X^(i-1),i=1..nops(L)); %p A091221 R:= Factors(P) mod 2; %p A091221 nops(R[2]); %p A091221 end proc: %p A091221 map(f, [$1.200]); # _Robert Israel_, Oct 11 2024 %Y A091221 a(n) = A001221(A091203(n)) = A001221(A091205(n)). A000374(n) = a(A000051(n)). %K A091221 nonn %O A091221 1,6 %A A091221 _Antti Karttunen_, Jan 03 2004