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 A090133 #21 May 09 2024 04:59:44
%S A090133 1,0,-5,20,-55,120,-205,220,145,-1680,5995,-15580,32345,-51480,44195,
%T A090133 80620,-543455,1770720,-4365605,8608820,-12607255,7384920,33496595,
%U A090133 -170910980,516160945,-1210088880,2259550795,-2987758780,653281145,12325669320
%N A090133 Expansion of (1+4x)/(1+4x+5x^2).
%D A090133 D. Cvijovic, J Klinowski, An Application for the Chebyshev Polynomials, Mat. Vesnik 50 (1998) 105-110
%H A090133 D. Cvijovic and J. Klinowski, <a href="http://www.komunikacija.org.rs/komunikacija/casopisi/matvesnik/50_3-4/d008/show_download">An Application for the Chebyshev Polynomials</a>, Mat. Vesnik 50 (1998) 105-110. [broken link]
%H A090133 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-4,-5).
%F A090133 a(n) = Sum_{k=0..n} C(n, k)*(-2)^(n-k)*(-1)^floor(k/2)*(1+(1-(-1)^k)/2).
%F A090133 a(n+1) = (-1)^n * (4*A099456(n) - A099456(n+1)). - _Ralf Stephan_, Jul 19 2013
%Y A090133 Cf. A099456.
%K A090133 easy,sign
%O A090133 0,3
%A A090133 _Paul Barry_, Nov 21 2003
%E A090133 Better name from _Ralf Stephan_, Jul 14 2013