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 A141125 #21 Jul 18 2025 11:13:31
%S A141125 1,4,-4,-16,16,64,-64,-256,256,1024,-1024,-4096,4096,16384,-16384,
%T A141125 -65536,65536,262144,-262144,-1048576,1048576,4194304,-4194304,
%U A141125 -16777216,16777216,67108864,-67108864,-268435456,268435456,1073741824,-1073741824,-4294967296,4294967296
%N A141125 Hankel transform of a transform of Fibonacci numbers.
%C A141125 Hankel transform of A100095(n+1).
%H A141125 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,-4).
%F A141125 G.f.: (1+4x)/(1+4x^2).
%F A141125 a(n) = 2^n*(cos(Pi*n/2)+2*sin(Pi*n/2)).
%F A141125 a(n+3) = a(n+2)*a(n+1)/a(n). - _Reinhard Zumkeller_, Mar 04 2011
%F A141125 E.g.f.: cos(2*x) + 2*sin(2*x). - _Stefano Spezia_, Jul 18 2025
%t A141125 LinearRecurrence[{0,-4},{1,4},33] (* or *) CoefficientList[Series[(1+4x)/(1+4x^2),{x,0,32}],x] (* _James C. McMahon_, Jul 17 2025 *)
%Y A141125 Cf. A100095, A141124.
%K A141125 easy,sign
%O A141125 0,2
%A A141125 _Paul Barry_, Jun 05 2008
%E A141125 More terms from _James C. McMahon_, Jul 18 2025