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Search: id:A107220
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| A107220 |
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Numbers n so that 1 + (x + x^3 + x^5 + x^7 + ...+ x^(2*n+1)) is irreducible over GF(2). |
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+0
1
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| 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)
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OFFSET
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1,2
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LINKS
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Joerg Arndt, draft of the fxtbook("Algorithms for programmers").
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EXAMPLE
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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)
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PROGRAM
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(PARI) for(d=1, 500, p=(1+sum(t=0, d, x^(2*t+1))); if(polisirreducible(Mod(1, 2)*p), print1(d, ", ")))
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CROSSREFS
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Sequence in context: A126278 A133847 A134180 this_sequence A098758 A029608 A145388
Adjacent sequences: A107217 A107218 A107219 this_sequence A107221 A107222 A107223
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KEYWORD
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nonn
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AUTHOR
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Joerg Arndt (arndt(AT)jjj.de), Jun 08 2005
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