This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A085435 #8 Jul 10 2018 02:03:19
%S A085435 3,9,63,225,1023,3969,16383,65025,262143,1046529,4194303,16769025,
%T A085435 67108863,268402689,1073741823,4294836225,17179869183,68718952449,
%U A085435 274877906943,1099509530625,4398046511103,17592177655809,70368744177663,281474943156225,1125899906842623
%N A085435 Resultant of the polynomial x^n-1 and the Chebyshev polynomial of the second kind U_2(x).
%F A085435 a(n) = 4^n - 2^n - (-2)^n + (-1)^n. Proof: Resultant(p, q) = (Leading Coefficient of q)^(Degree of p) * Product(p(i):i roots of q). - Luke Pebody, Oct 12 2004
%o A085435 (PARI) a(n)={polresultant(x^n-1, polchebyshev(2, 2, x))} \\ _Andrew Howroyd_, Jul 10 2018
%o A085435 (PARI) a(n)={4^n - 2^n - (-2)^n + (-1)^n} \\ _Andrew Howroyd_, Jul 10 2018
%Y A085435 Cf. A085903.
%K A085435 nonn
%O A085435 1,1
%A A085435 Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 18 2003
%E A085435 Terms a(11) and beyond from _Andrew Howroyd_, Jul 10 2018