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 A349076 #19 Feb 16 2025 08:34:02
%S A349076 1,6,143,5796,330049,24192090,2168392031,229755926568,28093745899009,
%T A349076 3893604149949966,603151411514453999,103272803655639197580,
%U A349076 19367259480582106560193,3947962681769909551857186,869179946261864224288867775,205535515565731164929726435280
%N A349076 a(n) = U(n, 3*n), where U(n, x) is the Chebyshev polynomial of the second kind.
%C A349076 In general, for k>=1, U(n, k*n) ~ 2^n * k^n * n^n.
%H A349076 Seiichi Manyama, <a href="/A349076/b349076.txt">Table of n, a(n) for n = 0..306</a>
%H A349076 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ChebyshevPolynomialoftheSecondKind.html">Chebyshev Polynomial of the Second Kind</a>.
%H A349076 Wikipedia, <a href="https://en.wikipedia.org/wiki/Chebyshev_polynomials">Chebyshev polynomials</a>.
%F A349076 a(n) = ((3*n + sqrt(9*n^2-1))^(n+1) - (3*n - sqrt(9*n^2-1))^(n+1)) / (2*sqrt(9*n^2-1)).
%F A349076 a(n) ~ 6^n * n^n.
%t A349076 Table[ChebyshevU[n, 3*n], {n, 0, 20}]
%o A349076 (PARI) a(n) = polchebyshev(n, 2, 3*n); \\ _Michel Marcus_, Nov 07 2021
%Y A349076 Cf. A323118, A349071, A349072, A349074, A349075.
%K A349076 nonn
%O A349076 0,2
%A A349076 _Vaclav Kotesovec_, Nov 07 2021