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 A099278 #8 Jul 02 2023 18:58:13
%S A099278 0,1,20,441,9680,212521,4665780,102434641,2248896320,49373284401,
%T A099278 1083963360500,23797820646601,522468090864720,11470500178377241,
%U A099278 251828535833434580,5528757288157183521,121380831803624602880
%N A099278 Unsigned member r=-20 of the family of Chebyshev sequences S_r(n) defined in A092184.
%C A099278 ((-1)^(n+1))*a(n) = S_{-20}(n), n>=0, defined in A092184.
%H A099278 <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%H A099278 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (21, 21, -1).
%F A099278 a(n)= (T(n, 11)-(-1)^n)/12, with Chebyshev's polynomials of the first kind evaluated at x=11: T(n, 11)=A077422(n)=((11+2*sqrt(30))^n + (11-2*sqrt(30))^n)/2.
%F A099278 a(n)= 22*a(n-1)-a(n-2)+2*(-1)^(n+1), n>=2, a(0)=0, a(1)=1.
%F A099278 a(n)= 21*a(n-1) + 21*a(n-2) - a(n-3), n>=3, a(0)=0, a(1)=1, a(2)=20.
%F A099278 G.f.: x*(1-x)/((1+x)*(1-22*x+x^2)) = x*(1-x)/(1-21*x-21*x^2+x^3) (from the Stephan link, see A092184).
%K A099278 nonn,easy
%O A099278 0,3
%A A099278 _Wolfdieter Lang_, Oct 18 2004