The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A091247 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A091247

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

#16 by OEIS Server at Fri Jan 17 09:14:33 EST 2025

LINKS

Antti Karttunen, <a href="/A091247/b091247_1.txt">Table of n, a(n) for n = 0..65537</a>

#15 by Michael De Vlieger at Fri Jan 17 09:14:33 EST 2025

STATUS

proposed

approved

Discussion

Fri Jan 17

09:14

OEIS Server: Installed first b-file as b091247.txt.

#14 by Antti Karttunen at Fri Jan 17 09:11:36 EST 2025

STATUS

editing

proposed

#13 by Antti Karttunen at Fri Jan 17 09:11:32 EST 2025

LINKS

Antti Karttunen, <a href="/A091247/b091247_1.txt">Table of n, a(n) for n = 0..65537</a>

STATUS

approved

editing

#12 by Bruno Berselli at Sun Apr 12 17:35:52 EDT 2015

STATUS

reviewed

approved

#11 by Joerg Arndt at Sun Apr 12 10:44:52 EDT 2015

STATUS

proposed

reviewed

#10 by Michel Marcus at Sun Apr 12 09:11:29 EDT 2015

STATUS

editing

proposed

#9 by Michel Marcus at Sun Apr 12 09:11:08 EDT 2015

LINKS

<a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

FORMULA

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

PROG

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

CROSSREFS

Cf. A066247, A091203, A091205, A091246.

a(n) = A066247(A091203(n)) = A066247(A091205(n)). Complementary to A091225. Partial sums give A091245. Cf. A091246.

STATUS

approved

editing

#8 by Russ Cox at Sat Mar 31 14:02:20 EDT 2012

AUTHOR

_Antti Karttunen (His-Firstname.His-Surname(AT)iki.fi), _, Jan 03 2004

Discussion

Sat Mar 31

14:02

OEIS Server: https://oeis.org/edit/global/913

#7 by Russ Cox at Sun Jul 10 18:42:46 EDT 2011

LINKS

<a href="/Sindx_index/Ge.html#GF2X">Index entries for sequences operating on GF(2)[X]-polynomials</a>

Discussion

Sun Jul 10

18:42

OEIS Server: https://oeis.org/edit/global/43