A091247 Characteristic function of A091242: 1 if the n-th GF(2)[X] polynomial is reducible, 0 otherwise.

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, 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, 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

Offset: 0

Author

Antti Karttunen, Jan 03 2004

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..65537
• A. Karttunen, Scheme-program for computing this sequence.
• Index entries for characteristic functions
• Index entries for sequences operating on GF(2)[X]-polynomials

Crossrefs

Cf. A066247, A091203, A091205, A091246.

Complementary to A091225. Partial sums give A091245.

Programs

PARI

a(n) = if (n<2, 0, ! polisirreducible(Mod(1,2)*Pol(binary(n)))); \\ Michel Marcus, Apr 12 2015

Formula

a(n) = A066247(A091203(n)) = A066247(A091205(n)).