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A020515 4^n - 2^n + 1. +0
10
1, 3, 13, 57, 241, 993, 4033, 16257, 65281, 261633, 1047553, 4192257, 16773121, 67100673, 268419073, 1073709057, 4294901761, 17179738113, 68719214593, 274877382657, 1099510579201 (list; graph; listen)
OFFSET

0,2

COMMENT

6th cyclotomic polynomial evaluated at powers of 2.

Referred to as Kasami-Welch numbers by Aubry et al. The first prime values are a(1) = 3, a(2) = 13, a(4) = 241, a(32) = 18446744069414584321, no more for n less than or equal to 100. [From Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 15 2009]

LINKS

Yves Aubry, Gary Mcguire, Francois Rodier, A few more functions that are not APN infinitely often, Sep 12, 2009. [From Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 15 2009]

FORMULA

G.f.: 1/(1-4*x)-1/(1-2*x)+1/(1-x). E.g.f.: e^(4*x)-e^(2*x)+e^x. [From Mohammad K. Azarian (azarian(AT)evansville.edu), Jan 15 2009]

MAPLE

with(numtheory, cyclotomic):seq(cyclotomic(6, 2**i), i=0..24);

CROSSREFS

Sequence in context: A095934 A151220 A151221 this_sequence A049086 A010921 A163606

Adjacent sequences: A020512 A020513 A020514 this_sequence A020516 A020517 A020518

KEYWORD

nonn

AUTHOR

Simon Plouffe (simon.plouffe(AT)gmail.com)

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.


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