A091221 Number of distinct irreducible polynomials dividing n-th GF(2)[X]-polynomial.

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, 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, 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

Offset: 1

Author

Antti Karttunen, Jan 03 2004

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• A. Karttunen, Scheme-program for computing this sequence.
• Index entries for sequences operating on GF(2)[X]-polynomials

Crossrefs

a(n) = A001221(A091203(n)) = A001221(A091205(n)). A000374(n) = a(A000051(n)).

Programs

Maple

f:= proc(n) local L,P,R,i;
  L:= convert(n,base,2);
  P:= add(L[i]*X^(i-1),i=1..nops(L));
  R:= Factors(P) mod 2;
  nops(R[2]);
end proc:
map(f, [$1.200]); # Robert Israel, Oct 11 2024