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 A086369 Number of factors over Q in the factorization of T_n(x) - 1 where T_n(x) is the Chebyshev polynomial of the first kind. 2

%I

%S 1,2,3,4,3,6,3,6,5,6,3,10,3,6,7,8,3,10,3,10,7,6,3,14,5,6,7,10,3,14,3,

%T 10,7,6,7,16,3,6,7,14,3,14,3,10,11,6,3,18,5,10,7,10,3,14,7,14,7,6,3,

%U 22,3,6,11,12,7,14,3,10,7,14,3,22,3,6,11,10,7,14,3,18

%N Number of factors over Q in the factorization of T_n(x) - 1 where T_n(x) is the Chebyshev polynomial of the first kind.

%C If p is an odd prime then a(p) = 3.

%H Antti Karttunen, <a href="/A086369/b086369.txt">Table of n, a(n) for n = 1..2049</a>

%o (PARI) a(n)={vecsum(factor(polchebyshev(n, 1, x)-1)[, 2])} \\ _Andrew Howroyd_, Jul 10 2018

%Y Cf. A086374.

%K nonn

%O 1,2

%A Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 08 2003

%E a(14) corrected and a(21)-a(80) added by _Andrew Howroyd_, Jul 10 2018

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Last modified December 5 18:48 EST 2021. Contains 349557 sequences. (Running on oeis4.)