|
Search: id:A107220
|
|
|
| A107220 |
|
Numbers n so that 1 + (x + x^3 + x^5 + x^7 + ...+ x^(2*n+1)) is irreducible over GF(2). |
|
+0
1
|
|
| 1, 3, 5, 7, 9, 13, 23, 27, 31, 37, 63, 69, 117, 119, 173, 219, 223, 247, 307, 363, 383, 495
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Joerg Arndt, draft of the fxtbook
|
|
EXAMPLE
|
The number 5 is in the sequence because x^11 + x^9 + x^7 + x^5 + x^3 + x + 1 is irreducible over GF(2) (and 11=2*5+1)
|
|
PROGRAM
|
(PARI) for(d=1, 500, p=(1+sum(t=0, d, x^(2*t+1))); if(polisirreducible(Mod(1, 2)*p), print1(d, ", ")))
|
|
CROSSREFS
|
Sequence in context: A126278 A133847 A134180 this_sequence A098758 A029608 A145388
Adjacent sequences: A107217 A107218 A107219 this_sequence A107221 A107222 A107223
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Joerg Arndt (arndt(AT)jjj.de), Jun 08 2005
|
|
|
Search completed in 0.002 seconds
|
