A086327 Number of factors over Q in the factorization of the Chebyshev polynomial of the second kind U_n(x).
1, 2, 2, 2, 4, 2, 3, 4, 4, 2, 6, 2, 4, 6, 4, 2, 7, 2, 6, 6, 4, 2, 8, 4, 4, 6, 6, 2, 10, 2, 5, 6, 4, 6, 10, 2, 4, 6, 8, 2, 10, 2, 6, 10, 4, 2, 10, 4, 7, 6, 6, 2, 10, 6, 8, 6, 4, 2, 14, 2, 4, 10, 6, 6, 10, 2, 6, 6, 10, 2, 13, 2, 4, 10, 6, 6, 10, 2, 10, 8, 4, 2, 14, 6, 4, 6, 8, 2, 16, 6, 6, 6, 4, 6, 12, 2, 7, 10, 10, 2, 10, 2, 8, 14, 4
Offset: 1
Keywords
Links
- Antti Karttunen, Table of n, a(n) for n = 1..1515
- Gerzson Kéri, The factorization of compressed Chebyshev polynomials and other polynomials related to multiple-angle formulas, Annales Univ. Sci. Budapest (Hungary, 2022) Sect. Comp., Vol. 53, 93-108.
Crossrefs
Programs
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PARI
a(n)={vecsum(factor(polchebyshev(n, 2, x))[, 2])} \\ Andrew Howroyd, Jul 10 2018
Extensions
a(11) corrected and a(19)-a(85) from Andrew Howroyd, Jul 10 2018
Terms a(86)-a(105) from Antti Karttunen, Sep 25 2018
Comments