

A020501


Cyclotomic polynomials at x=2.


6



2, 3, 1, 3, 5, 11, 7, 43, 17, 57, 31, 683, 13, 2731, 127, 331, 257, 43691, 73, 174763, 205, 5419, 2047, 2796203, 241, 1016801, 8191, 261633, 3277, 178956971, 151, 715827883, 65537, 1397419, 131071, 24214051
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OFFSET

0,1


COMMENTS

a(0) depends on the definition of the 0th cyclotomic polynomial; Maple defines it as x, but Mathematica defines it as 1.  T. D. Noe, Jul 23 2008 [a(0) = x is correct.  N. J. A. Sloane, Aug 01 2008]
A020501[2n] = A019320[n] for all odd n > 1. (Because if m > 1 is odd, then Phi_2m(x) = Phi_m(x) as demonstrated by Bloom).  Antti Karttunen, Aug 02 2001


LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000
D. M. Bloom, On the Coefficients of the Cyclotomic Polynomials, Amer.Math.Monthly 75, 372377, 1968.
Index entries for cyclotomic polynomials, values at X


MAPLE

with(numtheory, cyclotomic); f := n>subs(x=2, cyclotomic(n, x)); seq(f(i), i=0..64);


PROG

(PARI) a(n) = if (n, polcyclo(n, 2), 2); \\ Michel Marcus, Mar 05 2016


CROSSREFS

Cf. A020500, A020513.
Cf. A105603
Sequence in context: A067337 A180091 A047973 * A283878 A086404 A192852
Adjacent sequences: A020498 A020499 A020500 * A020502 A020503 A020504


KEYWORD

sign


AUTHOR

Simon Plouffe


STATUS

approved



